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References: <20231010100441.30950-1-jose.pekkarinen@foxhound.fi>
In-Reply-To: <20231010100441.30950-1-jose.pekkarinen@foxhound.fi>
From:   Peter Gonda <pgonda@google.com>
Date:   Tue, 10 Oct 2023 10:49:36 -0600
Message-ID: <CAMkAt6o7urak_kAjxEU4wtXv-mGOnyOYdcyhCRMfAG3MAOip0g@mail.gmail.com>
Subject: Re: [PATCH] kvm/sev: make SEV/SEV-ES asids configurable
To:     =?UTF-8?Q?Jos=C3=A9_Pekkarinen?= <jose.pekkarinen@foxhound.fi>
Cc:     seanjc@google.com, pbonzini@redhat.com, skhan@linuxfoundation.org,
        tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
        dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-kernel-mentees@lists.linuxfoundation.org
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On Tue, Oct 10, 2023 at 5:22=E2=80=AFAM Jos=C3=A9 Pekkarinen
<jose.pekkarinen@foxhound.fi> wrote:
>
> There are bioses that doesn't allow to configure the
> number of asids allocated for SEV/SEV-ES, for those
> cases, the default behaviour allocates all the asids
> for SEV, leaving no room for SEV-ES to have some fun.
> If the user request SEV-ES to be enabled, it will
> find the kernel just run out of resources and ignored
> user request. This following patch will address this
> issue by making the number of asids for SEV/SEV-ES
> configurable over kernel module parameters.
>

All this patch does is introduce an error case right? Because if the
BIOS hasn't actually configured those SEV-ES asids and KVM tries to
use an SEV as an SEV-ES asid commands to the ASP will fail, right?

What happens when you try to create an SEV-ES VM with this patch, when
the BIOS hasn't allocated any SEV-ES asids?