From 332a9979d4dd0b047aa16db201c50fcedbd56743 Mon Sep 17 00:00:00 2001
From: Henry Wang <Henry.Wang@arm.com>
Date: Mon, 6 Jun 2022 06:17:29 +0000
Subject: [PATCH 3/4] xen/arm, libxl: Implement XEN_DOMCTL_shadow_op for Arm
This commit implements the `XEN_DOMCTL_shadow_op` support in Xen
for Arm. The p2m pages pool size for xl guests is supposed to be
determined by `XEN_DOMCTL_shadow_op`. Hence, this commit:
- Introduces a function `p2m_domctl` and implements the subops
`XEN_DOMCTL_SHADOW_OP_SET_ALLOCATION` and
`XEN_DOMCTL_SHADOW_OP_GET_ALLOCATION` of `XEN_DOMCTL_shadow_op`.
- Adds the `XEN_DOMCTL_SHADOW_OP_SET_ALLOCATION` support in libxl.
Therefore enabling the setting of shadow memory pool size
when creating a guest from xl and getting shadow memory pool size
from Xen.
Note that the `XEN_DOMCTL_shadow_op` added in this commit is only
a dummy op, and the functionality of setting/getting p2m memory pool
size for xl guests will be added in following commits.
This is part of CVE-2022-33747 / XSA-409.
Signed-off-by: Henry Wang <Henry.Wang@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
---
tools/libs/light/libxl_arm.c | 12 ++++++++++++
xen/arch/arm/domctl.c | 32 ++++++++++++++++++++++++++++++++
2 files changed, 44 insertions(+)
diff --git a/tools/libs/light/libxl_arm.c b/tools/libs/light/libxl_arm.c
index 73a95e83af24..22a0c561bbc6 100644
--- a/tools/libs/light/libxl_arm.c
+++ b/tools/libs/light/libxl_arm.c
@@ -131,6 +131,18 @@ int libxl__arch_domain_create(libxl__gc *gc,
libxl__domain_build_state *state,
uint32_t domid)
{
+ libxl_ctx *ctx = libxl__gc_owner(gc);
+ unsigned int shadow_mb = DIV_ROUNDUP(d_config->b_info.shadow_memkb, 1024);
+
+ int r = xc_shadow_control(ctx->xch, domid,
+ XEN_DOMCTL_SHADOW_OP_SET_ALLOCATION,
+ &shadow_mb, 0);
+ if (r) {
+ LOGED(ERROR, domid,
+ "Failed to set %u MiB shadow allocation", shadow_mb);
+ return ERROR_FAIL;
+ }
+
return 0;
}
diff --git a/xen/arch/arm/domctl.c b/xen/arch/arm/domctl.c
index 1baf25c3d98b..9bf72e693019 100644
--- a/xen/arch/arm/domctl.c
+++ b/xen/arch/arm/domctl.c
@@ -47,11 +47,43 @@ static int handle_vuart_init(struct domain *d,
return rc;
}
+static long p2m_domctl(struct domain *d, struct xen_domctl_shadow_op *sc,
+ XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
+{
+ if ( unlikely(d == current->domain) )
+ {
+ printk(XENLOG_ERR "Tried to do a p2m domctl op on itself.\n");
+ return -EINVAL;
+ }
+
+ if ( unlikely(d->is_dying) )
+ {
+ printk(XENLOG_ERR "Tried to do a p2m domctl op on dying domain %u\n",
+ d->domain_id);
+ return -EINVAL;
+ }
+
+ switch ( sc->op )
+ {
+ case XEN_DOMCTL_SHADOW_OP_SET_ALLOCATION:
+ return 0;
+ case XEN_DOMCTL_SHADOW_OP_GET_ALLOCATION:
+ return 0;
+ default:
+ {
+ printk(XENLOG_ERR "Bad p2m domctl op %u\n", sc->op);
+ return -EINVAL;
+ }
+ }
+}
+
long arch_do_domctl(struct xen_domctl *domctl, struct domain *d,
XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
{
switch ( domctl->cmd )
{
+ case XEN_DOMCTL_shadow_op:
+ return p2m_domctl(d, &domctl->u.shadow_op, u_domctl);
case XEN_DOMCTL_cacheflush:
{
gfn_t s = _gfn(domctl->u.cacheflush.start_pfn);
--
2.37.1