From: Sean Christopherson <seanjc@google.com>
To: Tycho Andersen <tycho@kernel.org>
Cc: Ashish Kalra <ashish.kalra@amd.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
John Allen <john.allen@amd.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>,
Jonathan Corbet <corbet@lwn.net>,
Shuah Khan <skhan@linuxfoundation.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Thomas Gleixner <tglx@kernel.org>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Shuah Khan <shuah@kernel.org>,
linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
Kim Phillips <kim.phillips@amd.com>,
Alexey Kardashevskiy <aik@amd.com>,
Nikunj A Dadhania <nikunj@amd.com>,
Andrew Morton <akpm@linux-foundation.org>,
Randy Dunlap <rdunlap@infradead.org>,
Dapeng Mi <dapeng1.mi@linux.intel.com>,
Kees Cook <kees@kernel.org>, Marco Elver <elver@google.com>,
Jakub Kicinski <kuba@kernel.org>,
Li RongQing <lirongqing@baidu.com>,
Eric Biggers <ebiggers@kernel.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
linux-doc@vger.kernel.org, kvm@vger.kernel.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v2 3/4] KVM: SEV: Add the kvm-amd.rapl_disable module parameter
Date: Mon, 27 Apr 2026 14:20:10 -0700 [thread overview]
Message-ID: <ae_TCofu4bHP_Ch-@google.com> (raw)
In-Reply-To: <20260427204847.112899-4-tycho@kernel.org>
On Mon, Apr 27, 2026, Tycho Andersen wrote:
> From: "Tycho Andersen (AMD)" <tycho@kernel.org>
>
> Add a user-visible way to set the RAPL_DIS bit for SNP init.
>
> Since setting RAPL_DIS affects the whole system, put the module parameter
> in kvm_amd instead of in the CCP driver to hopefully make it more obvious
> to admins.
>
> Signed-off-by: Tycho Andersen (AMD) <tycho@kernel.org>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 5 +++++
> arch/x86/kvm/svm/sev.c | 8 ++++++++
> 2 files changed, 13 insertions(+)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 4d0f545fb3ec..2b50eed8664c 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -3207,6 +3207,11 @@ Kernel parameters
> max_snp_asid == min_sev_asid-1, will effectively make
> SEV-ES unusable.
>
> + kvm-amd.rapl_disable= [KVM,AMD] Whether to disable RAPL
> + (Running Average Power Limit) when initializing the SNP
> + firmware. This disables the counters for the entire system until an
> + SNP shutdown command is issued.
I'm pretty sure I said this earlier: KVM absolutely should not be able to disable
RAPL for the entire system. That needs to be a power management thing. KVM then
needs to communicate (and enforce?) the policy to userspace.
next prev parent reply other threads:[~2026-04-27 21:20 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-27 20:48 [PATCH v2 0/4] Allow disabling RAPL during SNP initialization Tycho Andersen
2026-04-27 20:48 ` [PATCH v2 1/4] crypto/ccp: Pass init_args to __sev_snp_init_locked() Tycho Andersen
2026-04-27 20:48 ` [PATCH v2 2/4] crypto/ccp: Support setting RAPL_DIS in SNP_INIT_EX Tycho Andersen
2026-04-27 20:48 ` [PATCH v2 3/4] KVM: SEV: Add the kvm-amd.rapl_disable module parameter Tycho Andersen
2026-04-27 21:20 ` Sean Christopherson [this message]
2026-04-27 20:48 ` [PATCH v2 4/4] KVM: selftests: Add a smoke test support for RAPL_DIS Tycho Andersen
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