From: Jim Mattson <jmattson@google.com>
To: Tina Zhang <zhang_wei@open-hieco.net>
Cc: Sean Christopherson <seanjc@google.com>,
kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
Shuah Khan <shuah@kernel.org>,
zhouyanjing@hygon.cn, linux-kselftest@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 7/8] KVM: nSVM: Advertise DecodeAssists to L1
Date: Fri, 4 Sep 2026 17:44:47 -0700 [thread overview]
Message-ID: <CALMp9eSTK_m4XMyBk2U10dhQo-ve+M8CmToVyFcS40o7RoSX7A@mail.gmail.com> (raw)
In-Reply-To: <20260824123954.315112-8-zhang_wei@open-hieco.net>
On Mon, Aug 24, 2026 at 5:40 AM Tina Zhang <zhang_wei@open-hieco.net> wrote:
>
> Advertise DecodeAssists to L1 now that KVM virtualizes the
> guest-visible DecodeAssist state in VMCB12: EXITINFO1 decode data for
> MOV CR/DR, INTn, and INVLPG exits, plus instruction bytes for nested
> page faults and intercepted #PF exits. INVLPGA's linear address remains
> available directly from the saved guest rAX, as required by the APM.
>
> Expose the feature only when supported by hardware, as KVM still relies
> on hardware DecodeAssists for VM-Exits that are reflected directly from
> L2.
>
> With DecodeAssists exposed, QEMU configurations that require the feature
> (e.g. "-cpu ...,+decodeassists,...,enforce") are no longer rejected.
>
> Signed-off-by: Tina Zhang <zhang_wei@open-hieco.net>
Once the implementation issues are addressed...
Reviewed-by: Jim Mattson <jmattson@google.com>
next prev parent reply other threads:[~2026-09-05 0:45 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-24 12:39 [PATCH v5 0/8] KVM: nSVM: Enable DecodeAssists for nested guests Tina Zhang
2026-08-24 12:39 ` [PATCH v5 1/8] KVM: x86: Add helper to provide intercept linear addresses Tina Zhang
2026-09-04 22:34 ` Jim Mattson
2026-09-06 0:57 ` Tina Zhang
2026-08-24 12:39 ` [PATCH v5 2/8] KVM: nSVM: Synthesize DecodeAssists EXITINFO for emulated intercepts Tina Zhang
2026-09-04 23:07 ` Jim Mattson
2026-09-06 2:24 ` Tina Zhang
2026-09-06 16:29 ` Jim Mattson
2026-08-24 12:39 ` [PATCH v5 3/8] KVM: nSVM: Track fresh hardware DecodeAssist bytes Tina Zhang
2026-09-04 23:42 ` Jim Mattson
2026-09-05 14:02 ` Tina Zhang
2026-08-24 12:39 ` [PATCH v5 4/8] KVM: nSVM: Propagate hardware DecodeAssist bytes to VMCB12 Tina Zhang
2026-09-04 23:58 ` Jim Mattson
2026-09-06 2:45 ` Tina Zhang
2026-08-24 12:39 ` [PATCH v5 5/8] KVM: nSVM: Use emulator bytes for synthesized nested #NPF Tina Zhang
2026-09-05 0:17 ` Jim Mattson
2026-09-06 5:33 ` Tina Zhang
2026-08-24 12:39 ` [PATCH v5 6/8] KVM: nSVM: Fetch missing DecodeAssist bytes for synthesized #NPF/#PF Tina Zhang
2026-09-05 0:39 ` Jim Mattson
2026-09-06 6:40 ` Tina Zhang
2026-09-06 16:33 ` Jim Mattson
2026-09-10 0:51 ` Sean Christopherson
2026-08-24 12:39 ` [PATCH v5 7/8] KVM: nSVM: Advertise DecodeAssists to L1 Tina Zhang
2026-09-05 0:44 ` Jim Mattson [this message]
2026-08-24 12:39 ` [PATCH v5 8/8] KVM: selftests: Add nested SVM DecodeAssists test Tina Zhang
2026-09-03 2:41 ` [PATCH v5 0/8] KVM: nSVM: Enable DecodeAssists for nested guests Tina Zhang
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