When the guest can execute the XSAVES/XRSTORS instructions, set the
hardware IA32_XSS MSR to guest/host values on VM-entry/VM-exit.
Note that vcpu->arch.ia32_xss is currently guaranteed to be 0 on AMD,
since there is no way to change it.
Suggested-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
Signed-off-by: Aaron Lewis <aaronlewis@xxxxxxxxxx>
Change-Id: Id51a782462086e6d7a3ab621838e200f1c005afd
---
arch/x86/kvm/svm.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index f64041368594..2702ebba24ba 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -115,6 +115,8 @@ MODULE_DEVICE_TABLE(x86cpu, svm_cpu_id);
static bool erratum_383_found __read_mostly;
+static u64 __read_mostly host_xss;
+
static const u32 host_save_user_msrs[] = {
#ifdef CONFIG_X86_64
MSR_STAR, MSR_LSTAR, MSR_CSTAR, MSR_SYSCALL_MASK, MSR_KERNEL_GS_BASE,
@@ -1400,6 +1402,9 @@ static __init int svm_hardware_setup(void)
pr_info("Virtual GIF supported\n");
}
+ if (boot_cpu_has(X86_FEATURE_XSAVES))
+ rdmsrl(MSR_IA32_XSS, host_xss);
+
return 0;
err:
@@ -5590,6 +5595,22 @@ static void svm_cancel_injection(struct kvm_vcpu *vcpu)
svm_complete_interrupts(svm);
}
+static void svm_load_guest_xss(struct kvm_vcpu *vcpu)
+{
+ if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) &&
+ vcpu->arch.xsaves_enabled &&
+ vcpu->arch.ia32_xss != host_xss)
+ wrmsrl(MSR_IA32_XSS, vcpu->arch.ia32_xss);
+}
+
+static void svm_load_host_xss(struct kvm_vcpu *vcpu)
+{
+ if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) &&
+ vcpu->arch.xsaves_enabled &&
+ vcpu->arch.ia32_xss != host_xss)
+ wrmsrl(MSR_IA32_XSS, host_xss);
+}
+
static void svm_vcpu_run(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
@@ -5629,6 +5650,7 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
clgi();
kvm_load_guest_xcr0(vcpu);
+ svm_load_guest_xss(vcpu);
if (lapic_in_kernel(vcpu) &&
vcpu->arch.apic->lapic_timer.timer_advance_ns)
@@ -5778,6 +5800,7 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
if (unlikely(svm->vmcb->control.exit_code == SVM_EXIT_NMI))
kvm_before_interrupt(&svm->vcpu);
+ svm_load_host_xss(vcpu);
kvm_put_guest_xcr0(vcpu);
stgi();
--
2.23.0.866.gb869b98d4c-goog
