From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Yang Weijiang <weijiang.yang@intel.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
pbonzini@redhat.com, jmattson@google.com,
yu.c.zhang@linux.intel.com
Subject: Re: [RESEND v13 06/11] KVM: x86: Load guest fpu state when access MSRs managed by XSAVES
Date: Wed, 22 Jul 2020 13:32:45 -0700 [thread overview]
Message-ID: <20200722203244.GG9114@linux.intel.com> (raw)
In-Reply-To: <20200716031627.11492-7-weijiang.yang@intel.com>
On Thu, Jul 16, 2020 at 11:16:22AM +0800, Yang Weijiang wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
>
> A handful of CET MSRs are not context switched through "traditional"
> methods, e.g. VMCS or manual switching, but rather are passed through
> to the guest and are saved and restored by XSAVES/XRSTORS, i.e. in the
> guest's FPU state.
>
> Load the guest's FPU state if userspace is accessing MSRs whose values
> are managed by XSAVES so that the MSR helper, e.g. vmx_{get,set}_msr(),
> can simply do {RD,WR}MSR to access the guest's value.
>
> Note that guest_cpuid_has() is not queried as host userspace is allowed
> to access MSRs that have not been exposed to the guest, e.g. it might do
> KVM_SET_MSRS prior to KVM_SET_CPUID2.
No comments on the patch itself. Added a blurb to the changelog to call
out the vcpu==NULL case is possible due to KVM_GET_MSRS also being a device
scope ioctl().
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Co-developed-by: Yang Weijiang <weijiang.yang@intel.com>
> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
next prev parent reply other threads:[~2020-07-22 20:32 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-16 3:16 [RESEND PATCH v13 00/11] Introduce support for guest CET feature Yang Weijiang
2020-07-16 3:16 ` [RESEND v13 01/11] KVM: x86: Include CET definitions for KVM test purpose Yang Weijiang
2020-07-16 3:16 ` [RESEND v13 02/11] KVM: VMX: Introduce CET VMCS fields and flags Yang Weijiang
2020-07-22 19:48 ` Sean Christopherson
2020-07-16 3:16 ` [RESEND v13 03/11] KVM: VMX: Set guest CET MSRs per KVM and host configuration Yang Weijiang
2020-07-22 20:14 ` Sean Christopherson
2020-07-16 3:16 ` [RESEND v13 04/11] KVM: VMX: Configure CET settings upon guest CR0/4 changing Yang Weijiang
2020-07-22 20:31 ` Sean Christopherson
2020-07-16 3:16 ` [RESEND v13 05/11] KVM: x86: Refresh CPUID once guest changes XSS bits Yang Weijiang
2020-07-22 20:32 ` Sean Christopherson
2020-07-16 3:16 ` [RESEND v13 06/11] KVM: x86: Load guest fpu state when access MSRs managed by XSAVES Yang Weijiang
2020-07-22 20:32 ` Sean Christopherson [this message]
2020-07-16 3:16 ` [RESEND v13 07/11] KVM: x86: Add userspace access interface for CET MSRs Yang Weijiang
2020-07-22 20:54 ` Sean Christopherson
2020-07-16 3:16 ` [RESEND v13 08/11] KVM: VMX: Enable CET support for nested VM Yang Weijiang
2020-07-22 21:20 ` Sean Christopherson
2020-07-16 3:16 ` [RESEND v13 09/11] KVM: VMX: Add VMCS dump and sanity check for CET states Yang Weijiang
2020-07-22 21:29 ` Sean Christopherson
2020-07-16 3:16 ` [RESEND v13 10/11] KVM: x86: Add #CP support in guest exception dispatch Yang Weijiang
2020-07-22 21:29 ` Sean Christopherson
2020-07-16 3:16 ` [RESEND v13 11/11] KVM: x86: Enable CET virtualization and advertise CET to userspace Yang Weijiang
2020-07-22 21:33 ` Sean Christopherson
2020-07-22 19:48 ` [RESEND PATCH v13 00/11] Introduce support for guest CET feature Sean Christopherson
2020-07-23 3:17 ` Yang Weijiang
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