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Commit 6a907cd0 authored by Radim Krčmář's avatar Radim Krčmář
Browse files

Revert "KVM: SVM: fix trashing of MSR_TSC_AUX" 

This reverts commit 9770404a.

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 2b23c3a6.

2b23c3a6 ("KVM: SVM: do not set MSR_TSC_AUX on 32-bit builds") is a
build fix for 9770404a and reverting them separately would only
break more bisections.

Cc: stable@vger.kernel.org
parent 2b23c3a6

arch/x86/kvm/svm.c

+3 −5
Original line number Diff line number Diff line
@@ -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);