From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Yang Weijiang <weijiang.yang@intel.com>,
rkrcmar@redhat.com, jmattson@google.com,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
mst@redhat.com, yu-cheng.yu@intel.com, yi.z.zhang@intel.com,
hjl.tools@gmail.com, Zhang Yi Z <yi.z.zhang@linux.intel.com>
Subject: Re: [PATCH v2 1/7] KVM:VMX: Define CET VMCS fields and bits
Date: Mon, 4 Mar 2019 10:56:21 -0800 [thread overview]
Message-ID: <20190304185621.GG17120@linux.intel.com> (raw)
In-Reply-To: <4d9a5393-163b-f32a-4657-cec54093ee88@redhat.com>
On Tue, Jan 29, 2019 at 04:19:34PM +0100, Paolo Bonzini wrote:
> On 28/01/19 11:33, Yang Weijiang wrote:
> >> There is no code in this series to pass these fields to and from
> >> userspace, and also to save/restore U_CET, INT_SSP_TAB, PL0_SSP and
> >> PL3_SSP across context switches.
> >>
> > The kernel consumes these MSRs, please see kernel CET patch:
> > https://lkml.org/lkml/fancy/2018/11/20/225
>
> Still, even if the kernel saves these fields across context switch in
> XSAVE areas, KVM must support accesses to the MSRs from userspace, for
> example in order to perform live migration.
>
> For example, when reading/writing these in kvm_set_msr or
> kvm_get_msr_common, you would have to do a read/write from the host
> MSRs. You also have to put kvm_load_guest_fpu/kvm_put_guest_fpu calls
> in __msr_io.
Paolo, can you elaborate on why KVM would read the host MSRs? Wouldn't
kvm_{get,set}_msr() pull the values from the VMCS when necessary?
next prev parent reply other threads:[~2019-03-04 18:56 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-22 20:59 [PATCH v2 0/7] This patch-set is to enable Guest CET support Yang Weijiang
2019-01-22 20:59 ` [PATCH v2 1/7] KVM:VMX: Define CET VMCS fields and bits Yang Weijiang
2019-01-25 18:02 ` Paolo Bonzini
2019-01-28 10:33 ` Yang Weijiang
2019-01-29 15:19 ` Paolo Bonzini
2019-01-29 8:29 ` Yang Weijiang
2019-01-30 8:32 ` Paolo Bonzini
2019-03-04 18:56 ` Sean Christopherson [this message]
2019-03-08 9:15 ` Paolo Bonzini
2019-03-08 15:50 ` Sean Christopherson
2019-03-08 16:34 ` Paolo Bonzini
2019-01-25 22:30 ` Sean Christopherson
2019-01-29 17:47 ` Jim Mattson
2019-01-29 18:01 ` Jim Mattson
[not found] ` <20190129182750.GB8156@linux.intel.com>
2019-01-29 8:34 ` Yang Weijiang
2019-01-22 20:59 ` [PATCH v2 2/7] KVM:CPUID: Define CET CPUID bits and CR4.CET master enable bit Yang Weijiang
2019-01-22 20:59 ` [PATCH v2 3/7] KVM:CPUID: Add CPUID support for CET xsaves component query Yang Weijiang
2019-01-25 17:57 ` Paolo Bonzini
2019-01-25 22:40 ` Sean Christopherson
2019-01-22 20:59 ` [PATCH v2 4/7] KVM:CPUID: Fix xsaves area size calculation for CPUID.(EAX=0xD,ECX=1) Yang Weijiang
2019-01-25 22:47 ` Sean Christopherson
2019-01-22 20:59 ` [PATCH v2 5/7] KVM:VMX: Pass through host CET related MSRs to Guest Yang Weijiang
2019-01-25 22:50 ` Sean Christopherson
2019-01-22 20:59 ` [PATCH v2 6/7] KVM:VMX: Load Guest CET via VMCS when CET is enabled in Guest Yang Weijiang
2019-01-25 22:56 ` Sean Christopherson
2019-01-30 15:16 ` Yang Weijiang
2019-01-22 20:59 ` [PATCH v2 7/7] KVM:X86: Enable MSR_IA32_XSS bit 11 and 12 for CET xsaves/xrstors Yang Weijiang
2019-01-25 23:03 ` Sean Christopherson
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