x86: make vcpu_reset() preemptible
... as dropping the old page tables may take significant amounts of
time.
This is part of CVE-2013-1918 / XSA-45.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Tim Deegan <tim@xen.org>
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -902,17 +902,16 @@ int arch_set_info_guest(
#undef c
}
-void arch_vcpu_reset(struct vcpu *v)
+int arch_vcpu_reset(struct vcpu *v)
{
if ( !is_hvm_vcpu(v) )
{
destroy_gdt(v);
- vcpu_destroy_pagetables(v, 0);
- }
- else
- {
- vcpu_end_shutdown_deferral(v);
+ return vcpu_destroy_pagetables(v);
}
+
+ vcpu_end_shutdown_deferral(v);
+ return 0;
}
/*
@@ -1933,7 +1932,7 @@ int domain_relinquish_resources(struct d
for_each_vcpu ( d, v )
{
/* Drop the in-use references to page-table bases. */
- ret = vcpu_destroy_pagetables(v, 1);
+ ret = vcpu_destroy_pagetables(v);
if ( ret )
return ret;
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3083,8 +3083,11 @@ static void hvm_s3_suspend(struct domain
for_each_vcpu ( d, v )
{
+ int rc;
+
vlapic_reset(vcpu_vlapic(v));
- vcpu_reset(v);
+ rc = vcpu_reset(v);
+ ASSERT(!rc);
}
vpic_reset(d);
--- a/xen/arch/x86/hvm/vlapic.c
+++ b/xen/arch/x86/hvm/vlapic.c
@@ -252,10 +252,13 @@ static void vlapic_init_sipi_action(unsi
{
case APIC_DM_INIT: {
bool_t fpu_initialised;
+ int rc;
+
domain_lock(target->domain);
/* Reset necessary VCPU state. This does not include FPU state. */
fpu_initialised = target->fpu_initialised;
- vcpu_reset(target);
+ rc = vcpu_reset(target);
+ ASSERT(!rc);
target->fpu_initialised = fpu_initialised;
vlapic_reset(vcpu_vlapic(target));
domain_unlock(target->domain);
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -2744,7 +2744,7 @@ static int put_old_guest_table(struct vc
return rc;
}
-int vcpu_destroy_pagetables(struct vcpu *v, bool_t preemptible)
+int vcpu_destroy_pagetables(struct vcpu *v)
{
unsigned long mfn = pagetable_get_pfn(v->arch.guest_table);
struct page_info *page;
@@ -2764,7 +2764,7 @@ int vcpu_destroy_pagetables(struct vcpu
if ( paging_mode_refcounts(v->domain) )
put_page(page);
else
- rc = put_page_and_type_preemptible(page, preemptible);
+ rc = put_page_and_type_preemptible(page, 1);
}
#ifdef __x86_64__
@@ -2790,7 +2790,7 @@ int vcpu_destroy_pagetables(struct vcpu
if ( paging_mode_refcounts(v->domain) )
put_page(page);
else
- rc = put_page_and_type_preemptible(page, preemptible);
+ rc = put_page_and_type_preemptible(page, 1);
}
if ( !rc )
v->arch.guest_table_user = pagetable_null();
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -770,14 +770,18 @@ int boot_vcpu(struct domain *d, int vcpu
return arch_set_info_guest(v, ctxt);
}
-void vcpu_reset(struct vcpu *v)
+int vcpu_reset(struct vcpu *v)
{
struct domain *d = v->domain;
+ int rc;
vcpu_pause(v);
domain_lock(d);
- arch_vcpu_reset(v);
+ set_bit(_VPF_in_reset, &v->pause_flags);
+ rc = arch_vcpu_reset(v);
+ if ( rc )
+ goto out_unlock;
set_bit(_VPF_down, &v->pause_flags);
@@ -793,9 +797,13 @@ void vcpu_reset(struct vcpu *v)
#endif
cpus_clear(v->cpu_affinity_tmp);
clear_bit(_VPF_blocked, &v->pause_flags);
+ clear_bit(_VPF_in_reset, &v->pause_flags);
+ out_unlock:
domain_unlock(v->domain);
vcpu_unpause(v);
+
+ return rc;
}
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -286,8 +286,10 @@ long do_domctl(XEN_GUEST_HANDLE(xen_domc
if ( guest_handle_is_null(op->u.vcpucontext.ctxt) )
{
- vcpu_reset(v);
- ret = 0;
+ ret = vcpu_reset(v);
+ if ( ret == -EAGAIN )
+ ret = hypercall_create_continuation(
+ __HYPERVISOR_domctl, "h", u_domctl);
goto svc_out;
}
--- a/xen/include/asm-x86/mm.h
+++ b/xen/include/asm-x86/mm.h
@@ -555,7 +555,7 @@ void audit_domains(void);
int new_guest_cr3(unsigned long pfn);
void make_cr3(struct vcpu *v, unsigned long mfn);
void update_cr3(struct vcpu *v);
-int vcpu_destroy_pagetables(struct vcpu *, bool_t preemptible);
+int vcpu_destroy_pagetables(struct vcpu *);
void propagate_page_fault(unsigned long addr, u16 error_code);
void *do_page_walk(struct vcpu *v, unsigned long addr);
--- a/xen/include/xen/domain.h
+++ b/xen/include/xen/domain.h
@@ -15,7 +15,7 @@ struct vcpu *alloc_vcpu(
int boot_vcpu(
struct domain *d, int vcpuid, vcpu_guest_context_u ctxt);
struct vcpu *alloc_dom0_vcpu0(void);
-void vcpu_reset(struct vcpu *v);
+int vcpu_reset(struct vcpu *);
struct xen_domctl_getdomaininfo;
void getdomaininfo(struct domain *d, struct xen_domctl_getdomaininfo *info);
@@ -57,7 +57,7 @@ void arch_dump_vcpu_info(struct vcpu *v)
void arch_dump_domain_info(struct domain *d);
-void arch_vcpu_reset(struct vcpu *v);
+int arch_vcpu_reset(struct vcpu *);
bool_t domctl_lock_acquire(void);
void domctl_lock_release(void);
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -597,6 +597,9 @@ extern struct domain *domain_list;
/* VCPU is blocked on memory-event ring. */
#define _VPF_mem_event 4
#define VPF_mem_event (1UL<<_VPF_mem_event)
+ /* VCPU is being reset. */
+#define _VPF_in_reset 7
+#define VPF_in_reset (1UL<<_VPF_in_reset)
static inline int vcpu_runnable(struct vcpu *v)
{