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Date: Wed, 18 Oct 2017 07:15:00 +0000 From: "Kang, Luwei" <luwei.kang@...el.com> To: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>, "kvm@...r.kernel.org" <kvm@...r.kernel.org> CC: "pbonzini@...hat.com" <pbonzini@...hat.com>, "rkrcmar@...hat.com" <rkrcmar@...hat.com>, "tglx@...utronix.de" <tglx@...utronix.de>, "mingo@...hat.com" <mingo@...hat.com>, "hpa@...or.com" <hpa@...or.com>, "x86@...nel.org" <x86@...nel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Chao Peng <chao.p.peng@...ux.intel.com> Subject: RE: [PATCH 9/9] KVM: x86: Disable intercept for Intel processor trace MSRs > On October 16, 2017 8:14:11 AM EDT, Luwei Kang <luwei.kang@...el.com> wrote: > >From: Chao Peng <chao.p.peng@...ux.intel.com> > > > >Trap for Intel processor trace is none sense. Pass through to guest > >directly. > > > And none of those MSRs can be subverted by the guest? That is none of these should be filtered / audited first? > Currently, I think it is no necessary. For example, host context(MSRs) would be saved and guest context would be restored before VM-entry in host-guest mode. And IA32_RTIT_CTL will be written with the value of the associated Guest State field of the VMCS on VM entry. I am not very clear what your point. Could you make a specific scenes? Thanks, Luwei Kang > > > > >Signed-off-by: Chao Peng <chao.p.peng@...ux.intel.com> > >Signed-off-by: Luwei Kang <luwei.kang@...el.com> > >--- > > arch/x86/kvm/vmx.c | 14 ++++++++++++++ > > 1 file changed, 14 insertions(+) > > > >diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index > >3c9ce3e..58606ce 100644 > >--- a/arch/x86/kvm/vmx.c > >+++ b/arch/x86/kvm/vmx.c > >@@ -7076,6 +7076,20 @@ static __init int hardware_setup(void) > > if (pt_mode == PT_MODE_GUEST) > > pt_register_virt_ops(&pt_virt_ops); > > > >+ if (pt_mode == PT_MODE_GUEST || pt_mode == PT_MODE_HOST_GUEST) { > >+ u32 i, eax, ebx, ecx, edx; > >+ > >+ cpuid_count(0x14, 1, &eax, &ebx, &ecx, &edx); > >+ vmx_disable_intercept_for_msr(MSR_IA32_RTIT_CTL, false); > >+ vmx_disable_intercept_for_msr(MSR_IA32_RTIT_STATUS, false); > >+ vmx_disable_intercept_for_msr(MSR_IA32_RTIT_OUTPUT_BASE, false); > >+ vmx_disable_intercept_for_msr(MSR_IA32_RTIT_OUTPUT_MASK, false); > >+ vmx_disable_intercept_for_msr(MSR_IA32_RTIT_CR3_MATCH, false); > >+ for (i = 0; i < (eax & 0x7); i++) > >+ vmx_disable_intercept_for_msr(MSR_IA32_RTIT_ADDR0_A + i, > >+ false); > >+ } > >+ > > return alloc_kvm_area(); > > > > out: > > > Thanks!
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