From: Sean Christopherson <seanjc@google.com>
To: Manali Shukla <manali.shukla@amd.com>
Cc: kvm@vger.kernel.org, linux-kselftest@vger.kernel.org,
pbonzini@redhat.com, shuah@kernel.org, nikunj@amd.com,
thomas.lendacky@amd.com, vkuznets@redhat.com, bp@alien8.de,
babu.moger@amd.com, neeraj.upadhyay@amd.com
Subject: Re: [PATCH v6 3/3] KVM: selftests: Add self IPI HLT test
Date: Tue, 25 Feb 2025 16:38:16 -0800 [thread overview]
Message-ID: <Z75iePyU3PK01oG7@google.com> (raw)
In-Reply-To: <20250128124812.7324-4-manali.shukla@amd.com>
On Tue, Jan 28, 2025, Manali Shukla wrote:
> + if (kvm_cpu_has(X86_FEATURE_IDLE_HLT))
Well, shoot. I gave you bad input, and we're stuck.
this_cpu_has() isn't correct, because the part of my previous feedback about
needing to check *KVM* support was 100% correct. But kvm_cpu_has() isn't right
either, because that checks what KVM supports exposing to the guest, not what
KVM itself supports/uses. E.g. even if we add full nested support, the test would
fail if nested=0 due to KVM not "supporting" Idle HLT despite using it under the
hood.
The lack of a way for KVM to communicate support to the user has come up in the
past, e.g. in discussion around /proc/cpuinfo. Sadly, AFAIK there are no (good)
ideas on what that should look like.
For now, I'll just skip this patch, even though doing so makes me quite sad.
next prev parent reply other threads:[~2025-02-26 0:38 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-28 12:48 [PATCH v6 0/3] Add support for the Idle HLT intercept feature Manali Shukla
2025-01-28 12:48 ` [PATCH v6 1/3] x86/cpufeatures: Add CPUID feature bit for Idle HLT intercept Manali Shukla
2025-01-28 12:48 ` [PATCH v6 2/3] KVM: SVM: Add Idle HLT intercept support Manali Shukla
2025-02-25 22:07 ` Sean Christopherson
2025-02-27 8:21 ` Manali Shukla
2025-02-27 14:32 ` Sean Christopherson
2025-02-27 16:05 ` Manali Shukla
2025-02-27 16:11 ` Sean Christopherson
2025-02-28 14:58 ` Manali Shukla
2025-01-28 12:48 ` [PATCH v6 3/3] KVM: selftests: Add self IPI HLT test Manali Shukla
2025-01-29 5:26 ` Neeraj Upadhyay
2025-02-26 0:38 ` Sean Christopherson [this message]
2025-02-28 15:05 ` Manali Shukla
2025-02-10 5:06 ` [PATCH v6 0/3] Add support for the Idle HLT intercept feature Manali Shukla
2025-02-17 4:43 ` Manali Shukla
2025-02-28 17:06 ` Sean Christopherson
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