From: Vishal Annapurve <vannapurve@google.com>
To: David Matlack <dmatlack@google.com>
Cc: x86 <x86@kernel.org>, kvm list <kvm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-kselftest@vger.kernel.org,
Paolo Bonzini <pbonzini@redhat.com>, shuah <shuah@kernel.org>,
Ben Gardon <bgardon@google.com>,
Sean Christopherson <seanjc@google.com>,
Oliver Upton <oupton@google.com>,
peterx@redhat.com, Vitaly Kuznetsov <vkuznets@redhat.com>,
drjones@redhat.com
Subject: Re: [V1 PATCH 3/5] selftests: kvm: x86: Execute vmcall/vmmcall according to CPU type
Date: Wed, 14 Sep 2022 12:12:16 -0700 [thread overview]
Message-ID: <CAGtprH9C9qTSBC8zB+q0K7ZgT=gs6hHy=i=1AQ80cD0U1vg7nA@mail.gmail.com> (raw)
In-Reply-To: <YxpysbHZb2G56K+f@google.com>
On Thu, Sep 8, 2022 at 3:54 PM David Matlack <dmatlack@google.com> wrote:
>
> Please use "KVM: selftest: ..." for the shortlog.
>
Ack.
> On Sat, Sep 03, 2022 at 01:28:47AM +0000, Vishal Annapurve wrote:
> > Modify following APIs for x86 implementation:
> > 1) kvm_arch_main : Query the cpu vendor and cache the value in advance.
> > 2) kvm_arch_post_vm_load: Populate cpu type in the guest memory so that
> > guest doesn't need to execute cpuid instruction again.
>
> This commit message only describes a subset of the changes in this
> commit, and does not provide any context on why the changes are being
> made (other than a clue about avoiding CPUID).
>
> I also think this could be split up into 2 separate commits.
>
Ack, will add more details to the commit log. Though since
is_amd_cpu/is_intel_cpu is used by both selftest VMM and selftest
guest logic, I would prefer to not split this change into two. For
now, I will upload the series with this change being a single patch.
We can discuss again if this split is really needed.
Regards,
Vishal
> I would suggest first patch changes is_{intel,amd}_cpu() to return a cached
> result. e.g.
>
> KVM: selftests: Precompute the result for is_{intel,amd}_cpu()
>
> Cache the vendor CPU type in a global variable so that multiple calls
> to is_intel_cpu() do not need to re-execute CPUID. This will be useful
> in a follow-up commit to check if running on AMD or Intel from within
> a selftest guest where executing CPUID requires a VM-exit.
>
> Then add support for AMD to kvm_hypercall():
>
> KVM: selftests: Add AMD support to kvm_hypercall()
>
> Add support for AMD hypercalls to kvm_hypercall() so that it can be
> used in selftests running on Intel or AMD hosts. This will be used in
> a follow up commit to ...
>
> As part of this change, sync the global variable is_cpu_amd into the
> guest so the guest can determine which hypercall instruction to use
> without needing to re-execute CPUID for every hypercall.
>
next prev parent reply other threads:[~2022-09-14 19:12 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-03 1:28 [V1 PATCH 0/5] Execute hypercalls from guests according to cpu type Vishal Annapurve
2022-09-03 1:28 ` [V1 PATCH 1/5] selftests: kvm: move common startup logic to kvm_util.c Vishal Annapurve
2022-09-08 21:09 ` David Matlack
2022-09-14 19:09 ` Vishal Annapurve
2022-09-03 1:28 ` [V1 PATCH 2/5] selftests: kvm: Introduce kvm_arch_main and helpers Vishal Annapurve
2022-09-05 7:46 ` Andrew Jones
2022-09-06 22:46 ` Vishal Annapurve
2022-09-08 21:21 ` David Matlack
2022-09-09 7:01 ` Andrew Jones
2022-09-14 19:13 ` Vishal Annapurve
2022-09-08 21:27 ` David Matlack
2022-09-03 1:28 ` [V1 PATCH 3/5] selftests: kvm: x86: Execute vmcall/vmmcall according to CPU type Vishal Annapurve
2022-09-08 22:54 ` David Matlack
2022-09-08 22:57 ` David Matlack
2022-09-14 19:12 ` Vishal Annapurve [this message]
2022-09-03 1:28 ` [V1 PATCH 4/5] selftests: kvm: delete svm_vmcall_test Vishal Annapurve
2022-09-03 1:28 ` [V1 PATCH 5/5] selftests: kvm: Execute vmcall/vmmcall as per cpu type Vishal Annapurve
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