[PATCH] KVM: SVM: Load %gs earlier if CONFIG_X86_32_LAZY_GS=n

[PATCH] KVM: SVM: Load %gs earlier if CONFIG_X86_32_LAZY_GS=n

[Avi Kivity]

With CONFIG_CC_STACKPROTECTOR, we need a valid %gs at all times, so disable
lazy reload and do an eager reload immediately after the vmexit.

Signed-off-by: Avi Kivity <avi@redhat.com>
---
 arch/x86/kvm/svm.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 8d61df4..6bb15d5 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1155,8 +1155,10 @@ static void svm_vcpu_put(struct kvm_vcpu *vcpu)
 	wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gs);
 	load_gs_index(svm->host.gs);
 #else
+#ifdef CONFIG_X86_32_LAZY_GS
 	loadsegment(gs, svm->host.gs);
 #endif
+#endif
 	for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++)
 		wrmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);
 }
@@ -3649,6 +3651,9 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
 	wrmsrl(MSR_GS_BASE, svm->host.gs_base);
 #else
 	loadsegment(fs, svm->host.fs);
+#ifndef CONFIG_X86_32_LAZY_GS
+	loadsegment(gs, svm->host.gs);
+#endif
 #endif
 
 	reload_tss(vcpu);
-- 
1.7.1

Re: [PATCH] KVM: SVM: Load %gs earlier if CONFIG_X86_32_LAZY_GS=n

[Roedel, Joerg]

On Tue, Mar 08, 2011 at 09:13:11AM -0500, Avi Kivity wrote:
> With CONFIG_CC_STACKPROTECTOR, we need a valid %gs at all times, so disable
> lazy reload and do an eager reload immediately after the vmexit.
>

Reported-by: IVAN ANGELOV <ivangotoy@gmail.com>

> Signed-off-by: Avi Kivity <avi@redhat.com>

Acked-By: Joerg Roedel <joerg.roedel@amd.com>

> ---
>  arch/x86/kvm/svm.c |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 8d61df4..6bb15d5 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -1155,8 +1155,10 @@ static void svm_vcpu_put(struct kvm_vcpu *vcpu)
>  	wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gs);
>  	load_gs_index(svm->host.gs);
>  #else
> +#ifdef CONFIG_X86_32_LAZY_GS
>  	loadsegment(gs, svm->host.gs);
>  #endif
> +#endif
>  	for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++)
>  		wrmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);
>  }
> @@ -3649,6 +3651,9 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
>  	wrmsrl(MSR_GS_BASE, svm->host.gs_base);
>  #else
>  	loadsegment(fs, svm->host.fs);
> +#ifndef CONFIG_X86_32_LAZY_GS
> +	loadsegment(gs, svm->host.gs);
> +#endif
>  #endif
>  
>  	reload_tss(vcpu);
> -- 
> 1.7.1
> 

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