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From db6ca8176ccc4ff7dfe3c06969af9ebfab0d7b04 Mon Sep 17 00:00:00 2001
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From: Andrew Cooper <andrew.cooper3@citrix.com>
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Date: Tue, 12 Jul 2022 11:13:33 +0200
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Subject: [PATCH] x86/spec-ctrl: Knobs for STIBP and PSFD, and follow hardware
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STIBP hint
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MIME-Version: 1.0
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Content-Type: text/plain; charset=utf8
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Content-Transfer-Encoding: 8bit
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STIBP and PSFD are slightly weird bits, because they're both implied by other
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bits in MSR_SPEC_CTRL. Add fine grain controls for them, and take the
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implications into account when setting IBRS/SSBD.
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Rearrange the IBPB text/variables/logic to keep all the MSR_SPEC_CTRL bits
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together, for consistency.
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However, AMD have a hardware hint CPUID bit recommending that STIBP be set
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unilaterally. This is advertised on Zen3, so follow the recommendation.
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Furthermore, in such cases, set STIBP behind the guest's back for now. This
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has negligible overhead for the guest, but saves a WRMSR on vmentry. This is
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the only default change.
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Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
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Reviewed-by: Jan Beulich <jbeulich@suse.com>
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Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
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master commit: fef244b179c06fcdfa581f7d57fa6e578c49ff50
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master date: 2022-06-30 18:07:13 +0100
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---
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docs/misc/xen-command-line.pandoc | 21 +++++++---
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xen/arch/x86/hvm/svm/vmcb.c | 9 +++++
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xen/arch/x86/spec_ctrl.c | 65 ++++++++++++++++++++++++++-----
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3 files changed, 81 insertions(+), 14 deletions(-)
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diff --git a/docs/misc/xen-command-line.pandoc b/docs/misc/xen-command-line.pandoc
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index a642e43476..46e9c58d35 100644
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--- a/docs/misc/xen-command-line.pandoc
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+++ b/docs/misc/xen-command-line.pandoc
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@@ -2234,8 +2234,9 @@ By default SSBD will be mitigated at runtime (i.e `ssbd=runtime`).
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### spec-ctrl (x86)
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> `= List of [ <bool>, xen=<bool>, {pv,hvm,msr-sc,rsb,md-clear}=<bool>,
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-> bti-thunk=retpoline|lfence|jmp, {ibrs,ibpb,ssbd,eager-fpu,
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-> l1d-flush,branch-harden,srb-lock,unpriv-mmio}=<bool> ]`
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+> bti-thunk=retpoline|lfence|jmp, {ibrs,ibpb,ssbd,psfd,
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+> eager-fpu,l1d-flush,branch-harden,srb-lock,
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+> unpriv-mmio}=<bool> ]`
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Controls for speculative execution sidechannel mitigations. By default, Xen
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will pick the most appropriate mitigations based on compiled in support,
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@@ -2285,9 +2286,10 @@ On hardware supporting IBRS (Indirect Branch Restricted Speculation), the
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If Xen is not using IBRS itself, functionality is still set up so IBRS can be
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virtualised for guests.
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-On hardware supporting IBPB (Indirect Branch Prediction Barrier), the `ibpb=`
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-option can be used to force (the default) or prevent Xen from issuing branch
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-prediction barriers on vcpu context switches.
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+On hardware supporting STIBP (Single Thread Indirect Branch Predictors), the
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+`stibp=` option can be used to force or prevent Xen using the feature itself.
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+By default, Xen will use STIBP when IBRS is in use (IBRS implies STIBP), and
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+when hardware hints recommend using it as a blanket setting.
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On hardware supporting SSBD (Speculative Store Bypass Disable), the `ssbd=`
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option can be used to force or prevent Xen using the feature itself. On AMD
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@@ -2295,6 +2297,15 @@ hardware, this is a global option applied at boot, and not virtualised for
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guest use. On Intel hardware, the feature is virtualised for guests,
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independently of Xen's choice of setting.
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+On hardware supporting PSFD (Predictive Store Forwarding Disable), the `psfd=`
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+option can be used to force or prevent Xen using the feature itself. By
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+default, Xen will not use PSFD. PSFD is implied by SSBD, and SSBD is off by
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+default.
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+
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+On hardware supporting IBPB (Indirect Branch Prediction Barrier), the `ibpb=`
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+option can be used to force (the default) or prevent Xen from issuing branch
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+prediction barriers on vcpu context switches.
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+
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On all hardware, the `eager-fpu=` option can be used to force or prevent Xen
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from using fully eager FPU context switches. This is currently implemented as
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a global control. By default, Xen will choose to use fully eager context
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diff --git a/xen/arch/x86/hvm/svm/vmcb.c b/xen/arch/x86/hvm/svm/vmcb.c
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index 565e997155..ef7224eb5d 100644
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--- a/xen/arch/x86/hvm/svm/vmcb.c
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+++ b/xen/arch/x86/hvm/svm/vmcb.c
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@@ -29,6 +29,7 @@
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#include <asm/hvm/support.h>
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#include <asm/hvm/svm/svm.h>
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ab31640 |
#include <asm/hvm/svm/svmdebug.h>
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+#include <asm/spec_ctrl.h>
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
struct vmcb_struct *alloc_vmcb(void)
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
{
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
@@ -176,6 +177,14 @@ static int construct_vmcb(struct vcpu *v)
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
vmcb->_pause_filter_thresh = SVM_PAUSETHRESH_INIT;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
}
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ /*
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ * When default_xen_spec_ctrl simply SPEC_CTRL_STIBP, default this behind
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ * the back of the VM too. Our SMT topology isn't accurate, the overhead
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ * is neglegable, and doing this saves a WRMSR on the vmentry path.
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ */
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ if ( default_xen_spec_ctrl == SPEC_CTRL_STIBP )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ v->arch.msrs->spec_ctrl.raw = SPEC_CTRL_STIBP;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
return 0;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
}
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
diff --git a/xen/arch/x86/spec_ctrl.c b/xen/arch/x86/spec_ctrl.c
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
index 1ed5ceda8b..dfdd45c358 100644
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
--- a/xen/arch/x86/spec_ctrl.c
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+++ b/xen/arch/x86/spec_ctrl.c
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
@@ -48,9 +48,13 @@ static enum ind_thunk {
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
THUNK_LFENCE,
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
THUNK_JMP,
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
} opt_thunk __initdata = THUNK_DEFAULT;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
static int8_t __initdata opt_ibrs = -1;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+int8_t __initdata opt_stibp = -1;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+bool __read_mostly opt_ssbd;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+int8_t __initdata opt_psfd = -1;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
bool __read_mostly opt_ibpb = true;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
-bool __read_mostly opt_ssbd = false;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
int8_t __read_mostly opt_eager_fpu = -1;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
int8_t __read_mostly opt_l1d_flush = -1;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
static bool __initdata opt_branch_harden = true;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
@@ -172,12 +176,20 @@ static int __init parse_spec_ctrl(const char *s)
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
else
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
rc = -EINVAL;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
}
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ /* Bits in MSR_SPEC_CTRL. */
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
else if ( (val = parse_boolean("ibrs", s, ss)) >= 0 )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
opt_ibrs = val;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
- else if ( (val = parse_boolean("ibpb", s, ss)) >= 0 )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
- opt_ibpb = val;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ else if ( (val = parse_boolean("stibp", s, ss)) >= 0 )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ opt_stibp = val;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
else if ( (val = parse_boolean("ssbd", s, ss)) >= 0 )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
opt_ssbd = val;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ else if ( (val = parse_boolean("psfd", s, ss)) >= 0 )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ opt_psfd = val;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ /* Misc settings. */
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ else if ( (val = parse_boolean("ibpb", s, ss)) >= 0 )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ opt_ibpb = val;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
else if ( (val = parse_boolean("eager-fpu", s, ss)) >= 0 )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
opt_eager_fpu = val;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
else if ( (val = parse_boolean("l1d-flush", s, ss)) >= 0 )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
@@ -376,7 +388,7 @@ static void __init print_details(enum ind_thunk thunk, uint64_t caps)
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
"\n");
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
/* Settings for Xen's protection, irrespective of guests. */
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
- printk(" Xen settings: BTI-Thunk %s, SPEC_CTRL: %s%s%s%s, Other:%s%s%s%s%s\n",
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ printk(" Xen settings: BTI-Thunk %s, SPEC_CTRL: %s%s%s%s%s, Other:%s%s%s%s%s\n",
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
thunk == THUNK_NONE ? "N/A" :
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
thunk == THUNK_RETPOLINE ? "RETPOLINE" :
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
thunk == THUNK_LFENCE ? "LFENCE" :
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
@@ -390,6 +402,9 @@ static void __init print_details(enum ind_thunk thunk, uint64_t caps)
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
(!boot_cpu_has(X86_FEATURE_SSBD) &&
|
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
!boot_cpu_has(X86_FEATURE_AMD_SSBD)) ? "" :
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
(default_xen_spec_ctrl & SPEC_CTRL_SSBD) ? " SSBD+" : " SSBD-",
|
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ (!boot_cpu_has(X86_FEATURE_PSFD) &&
|
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ !boot_cpu_has(X86_FEATURE_INTEL_PSFD)) ? "" :
|
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ (default_xen_spec_ctrl & SPEC_CTRL_PSFD) ? " PSFD+" : " PSFD-",
|
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
!(caps & ARCH_CAPS_TSX_CTRL) ? "" :
|
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
(opt_tsx & 1) ? " TSX+" : " TSX-",
|
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
!cpu_has_srbds_ctrl ? "" :
|
|
![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
@@ -979,10 +994,7 @@ void __init init_speculation_mitigations(void)
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|
![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
if ( !has_spec_ctrl )
|
|
![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
printk(XENLOG_WARNING "?!? CET active, but no MSR_SPEC_CTRL?\n");
|
|
![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
else if ( opt_ibrs == -1 )
|
|
![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
- {
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
opt_ibrs = ibrs = true;
|
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
- default_xen_spec_ctrl |= SPEC_CTRL_IBRS | SPEC_CTRL_STIBP;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
- }
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
if ( opt_thunk == THUNK_DEFAULT || opt_thunk == THUNK_RETPOLINE )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
thunk = THUNK_JMP;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
@@ -1086,14 +1098,49 @@ void __init init_speculation_mitigations(void)
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
setup_force_cpu_cap(X86_FEATURE_SC_MSR_HVM);
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
}
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
- /* If we have IBRS available, see whether we should use it. */
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ /* Figure out default_xen_spec_ctrl. */
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
if ( has_spec_ctrl && ibrs )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ {
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ /* IBRS implies STIBP. */
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ if ( opt_stibp == -1 )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ opt_stibp = 1;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
default_xen_spec_ctrl |= SPEC_CTRL_IBRS;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ }
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ /*
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ * Use STIBP by default if the hardware hint is set. Otherwise, leave it
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ * off as it a severe performance pentalty on pre-eIBRS Intel hardware
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ * where it was retrofitted in microcode.
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ */
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ if ( opt_stibp == -1 )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ opt_stibp = !!boot_cpu_has(X86_FEATURE_STIBP_ALWAYS);
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ if ( opt_stibp && (boot_cpu_has(X86_FEATURE_STIBP) ||
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ boot_cpu_has(X86_FEATURE_AMD_STIBP)) )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ default_xen_spec_ctrl |= SPEC_CTRL_STIBP;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
- /* If we have SSBD available, see whether we should use it. */
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
if ( opt_ssbd && (boot_cpu_has(X86_FEATURE_SSBD) ||
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
boot_cpu_has(X86_FEATURE_AMD_SSBD)) )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ {
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ /* SSBD implies PSFD */
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ if ( opt_psfd == -1 )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ opt_psfd = 1;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
default_xen_spec_ctrl |= SPEC_CTRL_SSBD;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ }
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ /*
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ * Don't use PSFD by default. AMD designed the predictor to
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ * auto-clear on privilege change. PSFD is implied by SSBD, which is
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ * off by default.
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ */
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ if ( opt_psfd == -1 )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ opt_psfd = 0;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ if ( opt_psfd && (boot_cpu_has(X86_FEATURE_PSFD) ||
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ boot_cpu_has(X86_FEATURE_INTEL_PSFD)) )
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
+ default_xen_spec_ctrl |= SPEC_CTRL_PSFD;
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
/*
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
* PV guests can create RSB entries for any linear address they control,
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
--
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
2.30.2
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![](https://seccdn.libravatar.org/avatar/f1a0ddfc363b14e167bf8548e95f340032d1964ae5b6ea4f235e351fd948008e?s=16&d=retro) |
ab31640 |
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