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-rw-r--r--arch/x86/kvm/x86.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 027dfd278a97..3bf2ecafd027 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5839,6 +5839,7 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
{
struct kvm_host_map map;
struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
+ u64 page_line_mask;
gpa_t gpa;
char *kaddr;
bool exchanged;
@@ -5853,7 +5854,16 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
(gpa & PAGE_MASK) == APIC_DEFAULT_PHYS_BASE)
goto emul_write;
- if (((gpa + bytes - 1) & PAGE_MASK) != (gpa & PAGE_MASK))
+ /*
+ * Emulate the atomic as a straight write to avoid #AC if SLD is
+ * enabled in the host and the access splits a cache line.
+ */
+ if (boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT))
+ page_line_mask = ~(cache_line_size() - 1);
+ else
+ page_line_mask = PAGE_MASK;
+
+ if (((gpa + bytes - 1) & page_line_mask) != (gpa & page_line_mask))
goto emul_write;
if (kvm_vcpu_map(vcpu, gpa_to_gfn(gpa), &map))