linux-kernel - Re: [V4 PATCH 0/4] Execute hypercalls according to host cpu

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Date:   Wed, 4 Jan 2023 11:32:44 -0800
From:   David Matlack <dmatlack@...gle.com>
To:     Vishal Annapurve <vannapurve@...gle.com>
Cc:     x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, pbonzini@...hat.com,
        shuah@...nel.org, bgardon@...gle.com, seanjc@...gle.com,
        oupton@...gle.com, peterx@...hat.com, vkuznets@...hat.com
Subject: Re: [V4 PATCH 0/4] Execute hypercalls according to host cpu

On Wed, Dec 28, 2022 at 07:24:34PM +0000, Vishal Annapurve wrote:
> Confidential VMs(CVMs) need to execute hypercall instruction as per the CPU
> type. Normally KVM emulates the vmcall/vmmcall instruction by patching
> the guest code at runtime. Such a guest memory manipulation by KVM is
> not allowed with CVMs and is also undesirable in general.
> 
> This series adds support of executing hypercall as per the host cpu
> type queried using cpuid instruction. CPU vendor type is stored early
> during selftest setup and guest setup to be reused later.
> 
> Changes in v4:
> 1) Incoporated suggestions from Sean -
>   * Added APIs to query host cpu type
>   * Shared the host cpu type with guests to avoid querying the cpu type
>     again
>   * Modified kvm_hypercall to execute vmcall/vmmcall according to host
>     cpu type.
> 2) Dropped the separate API for kvm_hypercall.
> 
> v3:
> https://lore.kernel.org/lkml/20221222230458.3828342-1-vannapurve@google.com/
> 
> Vishal Annapurve (4):
>   KVM: selftests: x86: use this_cpu_* helpers
>   KVM: selftests: x86: Add variables to store cpu type
>   KVM: sefltests: x86: Replace is_*cpu with is_host_*cpu
>   KVM: selftests: x86: Invoke kvm hypercall as per host cpu

For the series,

Reviewed-by: David Matlack <dmatlack@...gle.com>