[PATCH 3.2 05/87] KVM: x86: expose MSR_TSC_AUX to userspace
From: Ben Hutchings <hidden>
Date: 2016-02-09 00:25:45
Also in:
lkml
3.2.77-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Paolo Bonzini <pbonzini@redhat.com> commit 9dbe6cf941a6fe82933aef565e4095fb10f65023 upstream. If we do not do this, it is not properly saved and restored across migration. Windows notices due to its self-protection mechanisms, and is very upset about it (blue screen of death). Cc: Radim Krcmar <redacted> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> [bwh: Backported to 3.2: - We didn't yet have the switch() in kvm_init_msr_list as MPX is not supported at all - Adjust context] Signed-off-by: Ben Hutchings <redacted> ---
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c@@ -834,7 +834,8 @@ static u32 msrs_to_save[] = { #ifdef CONFIG_X86_64 MSR_CSTAR, MSR_KERNEL_GS_BASE, MSR_SYSCALL_MASK, MSR_LSTAR, #endif - MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA + MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA, + MSR_TSC_AUX, }; static unsigned num_msrs_to_save;
@@ -3867,6 +3868,20 @@ static void kvm_init_msr_list(void) for (i = j = KVM_SAVE_MSRS_BEGIN; i < ARRAY_SIZE(msrs_to_save); i++) { if (rdmsr_safe(msrs_to_save[i], &dummy[0], &dummy[1]) < 0) continue; + + /* + * Even MSRs that are valid in the host may not be exposed + * to the guests in some cases. + */ + switch (msrs_to_save[i]) { + case MSR_TSC_AUX: + if (!kvm_x86_ops->rdtscp_supported()) + continue; + break; + default: + break; + } + if (j < i) msrs_to_save[j] = msrs_to_save[i]; j++;