From: "Yosry Ahmed" <yosry.ahmed@linux.dev>
To: "Jim Mattson" <jmattson@google.com>
Cc: "Sean Christopherson" <seanjc@google.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Thomas Gleixner" <tglx@kernel.org>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
"Shuah Khan" <shuah@kernel.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v4 2/8] KVM: x86: nSVM: Cache and validate vmcb12 g_pat
Date: Fri, 20 Feb 2026 23:25:21 +0000 [thread overview]
Message-ID: <f67849d5dc11f19ab5835b6166e56d9a253d5ea2@linux.dev> (raw)
In-Reply-To: <CALMp9eTNpSDkEgVBb81n_vQrd63Txg+gMBCGh-DAcN5yOuhLxQ@mail.gmail.com>
February 21, 2026 at 12:26 AM, "Jim Mattson" <jmattson@google.com> wrote:
>
> On Thu, Feb 12, 2026 at 4:22 PM Yosry Ahmed <> wrote:
>
> >
> > @@ -2006,13 +2012,16 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu,
> >
> > /*
> > * Validate host state saved from before VMRUN (see
> > - * nested_svm_check_permissions).
> > + * nested_svm_check_permissions). Note that the g_pat field is not
> > + * validated, because (a) it may have been clobbered by SMM before
> > + * KVM_GET_NESTED_STATE, and (b) it is not loaded at emulated
> > + * #VMEXIT.
> >
> > (b) here means that svm_copy_vmrun_state() does not copy it to vmcb01,
> > and the value is restored by KVM_SET_MSRS, right?
> >
> Actually, (b) refers to the open-coded block of assignments in
> nested_svm_vmexit() under the comment:
>
> /*
> * Restore processor state that had been saved in vmcb01
> */
>
Yeah IIUC it's the same thing, we migrate them and copy them here to vmcb01 so that we can restore them in nested_svm_vmexit().
next prev parent reply other threads:[~2026-02-20 23:25 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-12 15:58 [PATCH v4 0/8] KVM: x86: nSVM: Improve PAT virtualization Jim Mattson
2026-02-12 15:58 ` [PATCH v4 1/8] KVM: x86: nSVM: Clear VMCB_NPT clean bit when updating hPAT from guest mode Jim Mattson
2026-02-13 0:17 ` Yosry Ahmed
2026-02-13 15:26 ` Sean Christopherson
2026-02-13 15:32 ` Yosry Ahmed
2026-02-13 15:46 ` Jim Mattson
2026-02-12 15:58 ` [PATCH v4 2/8] KVM: x86: nSVM: Cache and validate vmcb12 g_pat Jim Mattson
2026-02-13 0:22 ` Yosry Ahmed
2026-02-20 22:26 ` Jim Mattson
2026-02-20 23:25 ` Yosry Ahmed [this message]
2026-02-12 15:58 ` [PATCH v4 3/8] KVM: x86: nSVM: Set vmcb02.g_pat correctly for nested NPT Jim Mattson
2026-02-13 0:27 ` Yosry Ahmed
2026-02-12 15:58 ` [PATCH v4 4/8] KVM: x86: nSVM: Redirect IA32_PAT accesses to either hPAT or gPAT Jim Mattson
2026-02-13 0:30 ` Yosry Ahmed
2026-02-13 15:20 ` Sean Christopherson
2026-02-13 15:42 ` Jim Mattson
2026-02-13 22:19 ` Sean Christopherson
2026-02-13 23:31 ` Jim Mattson
2026-02-17 23:27 ` Sean Christopherson
2026-02-17 23:40 ` Yosry Ahmed
2026-02-17 23:44 ` Sean Christopherson
2026-03-26 21:18 ` Jim Mattson
2026-03-26 21:26 ` Yosry Ahmed
2026-03-26 21:56 ` Jim Mattson
2026-03-26 21:59 ` Yosry Ahmed
2026-02-13 15:43 ` Yosry Ahmed
2026-02-13 15:44 ` Yosry Ahmed
2026-02-12 15:58 ` [PATCH v4 5/8] KVM: x86: nSVM: Save gPAT to vmcb12.g_pat on VMEXIT Jim Mattson
2026-02-13 0:33 ` Yosry Ahmed
2026-02-12 15:58 ` [PATCH v4 6/8] KVM: x86: nSVM: Save/restore gPAT with KVM_{GET,SET}_NESTED_STATE Jim Mattson
2026-02-13 0:36 ` Yosry Ahmed
2026-02-12 15:58 ` [PATCH v4 7/8] KVM: x86: nSVM: Handle restore of legacy nested state Jim Mattson
2026-02-13 0:38 ` Yosry Ahmed
2026-02-12 15:58 ` [PATCH v4 8/8] KVM: selftests: nSVM: Add svm_nested_pat test Jim Mattson
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