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KVM: x86: Fix xsave cpuid exposing bug 

From 00c920c96127d20d4c3bb790082700ae375c39a0 Mon Sep 17 00:00:00 2001
From: Liu Jinsong <jinsong.liu@intel.com>
Date: Fri, 21 Feb 2014 23:47:18 +0800
Subject: [PATCH] KVM: x86: Fix xsave cpuid exposing bug

EBX of cpuid(0xD, 0) is dynamic per XCR0 features enable/disable.
Bit 63 of XCR0 is reserved for future expansion.

Signed-off-by: Liu Jinsong <jinsong.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Liu, Jinsong 2014-02-21 17:39:02 +00:00 committed by Paolo Bonzini
parent 49345f13f0
commit 56c103ec04
3 changed files with 10 additions and 5 deletions
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2
arch/x86/include/asm/xsave.h
View File

@ -13,6 +13,8 @@
#define XSTATE_BNDCSR 0x10 #define XSTATE_BNDCSR 0x10
#define XSTATE_FPSSE (XSTATE_FP | XSTATE_SSE) #define XSTATE_FPSSE (XSTATE_FP | XSTATE_SSE)
/* Bit 63 of XCR0 is reserved for future expansion */
#define XSTATE_EXTEND_MASK (~(XSTATE_FPSSE | (1ULL << 63)))
#define FXSAVE_SIZE 512 #define FXSAVE_SIZE 512

6
arch/x86/kvm/cpuid.c
View File

@ -28,7 +28,7 @@ static u32 xstate_required_size(u64 xstate_bv)
int feature_bit = 0; int feature_bit = 0;
u32 ret = XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET; u32 ret = XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET;
xstate_bv &= ~XSTATE_FPSSE; xstate_bv &= XSTATE_EXTEND_MASK;
while (xstate_bv) { while (xstate_bv) {
if (xstate_bv & 0x1) { if (xstate_bv & 0x1) {
u32 eax, ebx, ecx, edx; u32 eax, ebx, ecx, edx;
@ -74,8 +74,8 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu)
vcpu->arch.guest_supported_xcr0 = vcpu->arch.guest_supported_xcr0 =
(best->eax | ((u64)best->edx << 32)) & (best->eax | ((u64)best->edx << 32)) &
host_xcr0 & KVM_SUPPORTED_XCR0; host_xcr0 & KVM_SUPPORTED_XCR0;
vcpu->arch.guest_xstate_size = vcpu->arch.guest_xstate_size = best->ebx =
xstate_required_size(vcpu->arch.guest_supported_xcr0); xstate_required_size(vcpu->arch.xcr0);
} }
kvm_pmu_cpuid_update(vcpu); kvm_pmu_cpuid_update(vcpu);

7
arch/x86/kvm/x86.c
View File

@ -595,13 +595,13 @@ static void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu)
int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr) int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
{ {
u64 xcr0; u64 xcr0 = xcr;
u64 old_xcr0 = vcpu->arch.xcr0;
u64 valid_bits; u64 valid_bits;
/* Only support XCR_XFEATURE_ENABLED_MASK(xcr0) now */ /* Only support XCR_XFEATURE_ENABLED_MASK(xcr0) now */
if (index != XCR_XFEATURE_ENABLED_MASK) if (index != XCR_XFEATURE_ENABLED_MASK)
return 1; return 1;
xcr0 = xcr;
if (!(xcr0 & XSTATE_FP)) if (!(xcr0 & XSTATE_FP))
return 1; return 1;
if ((xcr0 & XSTATE_YMM) && !(xcr0 & XSTATE_SSE)) if ((xcr0 & XSTATE_YMM) && !(xcr0 & XSTATE_SSE))
@ -618,6 +618,9 @@ int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
kvm_put_guest_xcr0(vcpu); kvm_put_guest_xcr0(vcpu);
vcpu->arch.xcr0 = xcr0; vcpu->arch.xcr0 = xcr0;
if ((xcr0 ^ old_xcr0) & XSTATE_EXTEND_MASK)
kvm_update_cpuid(vcpu);
return 0; return 0;
} }