CPUID(0xd, 1) reports the current required storage size of XCR0 | XSS,
when guest updates the XSS, it's necessary to update the CPUID leaf, otherwise
guest will fetch old state size, and results to some WARN traces during guest
running.
supported_xss is initialized to host_xss & KVM_SUPPORTED_XSS to indicate current
MSR_IA32_XSS bits supported in KVM, but actual XSS bits seen in guest depends
on the setting of CPUID(0xd,1).{ECX, EDX} for guest.
Co-developed-by: Zhang Yi Z <yi.z.zhang@xxxxxxxxxxxxxxx>
Signed-off-by: Zhang Yi Z <yi.z.zhang@xxxxxxxxxxxxxxx>
Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/cpuid.c | 23 +++++++++++++++++++----
arch/x86/kvm/x86.c | 12 ++++++++----
3 files changed, 28 insertions(+), 8 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index be5363b21540..e8c749596ba2 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -654,6 +654,7 @@ struct kvm_vcpu_arch {
u64 xcr0;
u64 guest_supported_xcr0;
+ u64 guest_supported_xss;
struct kvm_pio_request pio;
void *pio_data;
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 8a294f9747aa..d97b2a6e8a8c 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -88,14 +88,29 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu)
vcpu->arch.guest_supported_xcr0 = 0;
} else {
vcpu->arch.guest_supported_xcr0 =
- (best->eax | ((u64)best->edx << 32)) & supported_xcr0;
+ (((u64)best->edx << 32) | best->eax) & supported_xcr0;
best->ebx = xstate_required_size(vcpu->arch.xcr0, false);
}
best = kvm_find_cpuid_entry(vcpu, 0xD, 1);
- if (best && (cpuid_entry_has(best, X86_FEATURE_XSAVES) ||
- cpuid_entry_has(best, X86_FEATURE_XSAVEC)))
- best->ebx = xstate_required_size(vcpu->arch.xcr0, true);
+ if (best) {
+ if (cpuid_entry_has(best, X86_FEATURE_XSAVES) ||
+ cpuid_entry_has(best, X86_FEATURE_XSAVEC)) {
+ u64 xstate = vcpu->arch.xcr0 | vcpu->arch.ia32_xss;
+
+ best->ebx = xstate_required_size(xstate, true);
+ }
+
+ if (!cpuid_entry_has(best, X86_FEATURE_XSAVES)) {
+ best->ecx = 0;
+ best->edx = 0;
+ }
+ vcpu->arch.guest_supported_xss =
+ (((u64)best->edx << 32) | best->ecx) & supported_xss;
+
+ } else {
+ vcpu->arch.guest_supported_xss = 0;
+ }
/*
* The existing code assumes virtual address is 48-bit or 57-bit in the
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 906e07039d59..8aed32ff9c0c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2912,9 +2912,12 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
* IA32_XSS[bit 8]. Guests have to use RDMSR/WRMSR rather than
* XSAVES/XRSTORS to save/restore PT MSRs.
*/
- if (data & ~supported_xss)
+ if (data & ~vcpu->arch.guest_supported_xss)
return 1;
- vcpu->arch.ia32_xss = data;
+ if (vcpu->arch.ia32_xss != data) {
+ vcpu->arch.ia32_xss = data;
+ kvm_update_cpuid(vcpu);
+ }
break;
case MSR_SMI_COUNT:
if (!msr_info->host_initiated)
@@ -9779,8 +9782,9 @@ int kvm_arch_hardware_setup(void *opaque)
memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
- if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
- supported_xss = 0;
+ supported_xss = 0;
+ if (kvm_cpu_cap_has(X86_FEATURE_XSAVES))
+ supported_xss = host_xss & KVM_SUPPORTED_XSS;
#define __kvm_cpu_cap_has(UNUSED_, f) kvm_cpu_cap_has(f)
cr4_reserved_bits = __cr4_reserved_bits(__kvm_cpu_cap_has, UNUSED_);
--
2.17.2
