From: Sean Christopherson <seanjc@google.com>
To: Ashish Kalra <Ashish.Kalra@amd.com>
Cc: pbonzini@redhat.com, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org,
hpa@zytor.com, thomas.lendacky@amd.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, joro@8bytes.org
Subject: Re: [PATCH v3] x86/sev: Add support for allowing zero SEV ASIDs.
Date: Wed, 31 Jan 2024 14:15:08 -0800 [thread overview]
Message-ID: <ZbrGbLLvdwRfMun5@google.com> (raw)
In-Reply-To: <20240104190520.62510-1-Ashish.Kalra@amd.com>
On Thu, Jan 04, 2024, Ashish Kalra wrote:
> From: Ashish Kalra <ashish.kalra@amd.com>
>
> Some BIOSes allow the end user to set the minimum SEV ASID value
> (CPUID 0x8000001F_EDX) to be greater than the maximum number of
> encrypted guests, or maximum SEV ASID value (CPUID 0x8000001F_ECX)
> in order to dedicate all the SEV ASIDs to SEV-ES or SEV-SNP.
>
> The SEV support, as coded, does not handle the case where the minimum
> SEV ASID value can be greater than the maximum SEV ASID value.
> As a result, the following confusing message is issued:
>
> [ 30.715724] kvm_amd: SEV enabled (ASIDs 1007 - 1006)
>
> Fix the support to properly handle this case.
>
> Fixes: 916391a2d1dc ("KVM: SVM: Add support for SEV-ES capability in KVM")
> Suggested-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
> Cc: stable@vger.kernel.org
> ---
> arch/x86/kvm/svm/sev.c | 40 ++++++++++++++++++++++++----------------
This should be ~3 patches:
1. Convert ASID variables/params to unsigned integers.
2. Return -EINVAL instead of -EBUSY
3. The actual fix here
E.g if #2 breaks userspace (extremely unlikely) then bisection should point at
exactly that, not at a commit with a whole pile of unrelated things going on.
I'll send a v4, #1 should also be accompanied by a cleanup of sev_asid_new() to
not multiplex the ASID with the return code. It can simply set sev->asid directly,
which as a bonus makes sev_asid_new() and sev_asid_free() more symmetric.
prev parent reply other threads:[~2024-01-31 22:15 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-04 19:05 [PATCH v3] x86/sev: Add support for allowing zero SEV ASIDs Ashish Kalra
2024-01-11 20:34 ` Tom Lendacky
2024-01-31 22:15 ` Sean Christopherson [this message]
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