Messages in this thread | | | Date | Thu, 19 Jun 2014 13:22:33 +0200 | From | Paolo Bonzini <> | Subject | Re: [PATCH] kvm: fix hyperv tsc page clear wrong address |
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Il 19/06/2014 13:17, "newtongao(高小明)" ha scritto: > This is more concisely > > From 6ddeb18347f9dda0fe37702e0d067a4129a89b54 Mon Sep 17 00:00:00 2001 > From: Xiaoming Gao <newtongao@tencent.com> > Date: Thu, 19 Jun 2014 19:14:57 +0800 > Subject: [PATCH] kvm: fix hyperv tsc page clear wrong address > > tsc page addr need clear the low HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT bits > before kvm_write_guest write the zero tsc_ref structure to guest, or it will lead > guest to get wrong clocksource. > > windows guest will get strong impact, QueryPerformanceCounter will always return 0 > ,all things in windows rely on clock source, will in serious chaos.
Right, this can happen if Windows passes a non-zero page to KVM.
Thanks,
Paolo
> Signed-off-by: Xiaoming Gao <newtongao@tencnet.com> > --- > arch/x86/kvm/x86.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index f32a025..f644933 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1898,7 +1898,7 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data) > if (!(data & HV_X64_MSR_TSC_REFERENCE_ENABLE)) > break; > gfn = data >> HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT; > - if (kvm_write_guest(kvm, data, > + if (kvm_write_guest(kvm, gfn << HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT, > &tsc_ref, sizeof(tsc_ref))) > return 1; > mark_page_dirty(kvm, gfn); >
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