openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

Revert "KVM: SVM: fix trashing of MSR_TSC_AUX" 

This reverts commit 9770404a00.

The reverted patch is not needed as only userspace uses RDTSCP and
MSR_TSC_AUX is in host_save_user_msrs[] and therefore properly saved in
svm_vcpu_load() and restored in svm_vcpu_put() before every switch to
userspace.

The reverted patch did not allow the kernel to use RDTSCP in the future,
because of missed trashing in svm_set_msr() and 64-bit ifdef.

This reverts commit 2b23c3a6e3.

2b23c3a6e3 ("KVM: SVM: do not set MSR_TSC_AUX on 32-bit builds") is a
build fix for 9770404a00 and reverting them separately would only
break more bisections.

Cc: stable@vger.kernel.org
This commit is contained in:
Radim Krčmář 2016-07-15 14:38:36 +02:00
parent 2b23c3a6e3
commit 6a907cd0ad
1 changed files with 3 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/x86/kvm/svm.c
View File

@ -41,7 +41,6 @@
#include <asm/desc.h>
#include <asm/debugreg.h>
#include <asm/kvm_para.h>
#include <asm/vgtod.h>
#include <asm/virtext.h>
#include "trace.h"
@ -1531,6 +1530,9 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
wrmsrl(MSR_AMD64_TSC_RATIO, tsc_ratio);
}
}
/* This assumes that the kernel never uses MSR_TSC_AUX */
if (static_cpu_has(X86_FEATURE_RDTSCP))
wrmsrl(MSR_TSC_AUX, svm->tsc_aux);
avic_vcpu_load(vcpu, cpu);
}
@ -4472,8 +4474,6 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
svm->vmcb->save.cr2 = vcpu->arch.cr2;
clgi();
if (static_cpu_has(X86_FEATURE_RDTSCP))
wrmsrl(MSR_TSC_AUX, svm->tsc_aux);
local_irq_enable();
@ -4551,8 +4551,6 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
);
#ifdef CONFIG_X86_64
if (static_cpu_has(X86_FEATURE_RDTSCP))
wrmsrl(MSR_TSC_AUX, __getcpu());
wrmsrl(MSR_GS_BASE, svm->host.gs_base);
#else
loadsegment(fs, svm->host.fs);