From: Dave Hansen <dave.hansen@intel.com>
To: Ashish Kalra <Ashish.Kalra@amd.com>,
corbet@lwn.net, seanjc@google.com, pbonzini@redhat.com,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, hpa@zytor.com,
herbert@gondor.apana.org.au, akpm@linux-foundation.org,
paulmck@kernel.org, rostedt@goodmis.org
Cc: x86@kernel.org, thuth@redhat.com, ardb@kernel.org,
gregkh@linuxfoundation.org, john.allen@amd.com,
davem@davemloft.net, thomas.lendacky@amd.com,
michael.roth@amd.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
linux-doc@vger.kernel.org
Subject: Re: [PATCH v4 5/5] KVM: SEV: Add SEV-SNP CipherTextHiding support
Date: Fri, 23 May 2025 10:29:48 -0700 [thread overview]
Message-ID: <f76327dd-b505-4a24-938c-5b917da9aff2@intel.com> (raw)
In-Reply-To: <e663930ca516aadbd71422af66e6939dd77e7b06.1747696092.git.ashish.kalra@amd.com>
On 5/19/25 17:02, Ashish Kalra wrote:
> + kvm-amd.ciphertext_hiding_nr_asids=
> + [KVM,AMD] Enables SEV-SNP CipherTextHiding feature and
> + controls show many ASIDs are available for SEV-SNP guests.
> + The ASID space is basically split into legacy SEV and
> + SEV-ES+. CipherTextHiding feature further splits the
> + SEV-ES+ ASID space into SEV-ES and SEV-SNP.
> + If the value is -1, then it is used as an auto flag
> + and splits the ASID space equally between SEV-ES and
> + SEV-SNP ASIDs.
This help text isn't great.
It doesn't come out and say what the connection between CipherTextHiding
and SEV-ES+. It's also impossible to choose a good number without
knowing how large the ASID space is in the first place.
Why use "-1"? Why not just take "auto" as a parameter?
It also needs to say what CipherTextHiding is in the first place and be
more clear about what the tradeoffs are from enabling this.
next prev parent reply other threads:[~2025-05-23 17:29 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-19 23:56 [PATCH v4 0/5] Add SEV-SNP CipherTextHiding feature support Ashish Kalra
2025-05-19 23:56 ` [PATCH v4 1/5] crypto: ccp: New bit-field definitions for SNP_PLATFORM_STATUS command Ashish Kalra
2025-06-03 14:03 ` Tom Lendacky
2025-05-19 23:56 ` [PATCH v4 2/5] crypto: ccp: Add support for SNP_FEATURE_INFO command Ashish Kalra
2025-06-03 15:21 ` Tom Lendacky
2025-06-04 22:52 ` Kalra, Ashish
2025-06-05 15:51 ` Tom Lendacky
2025-06-05 4:49 ` Alexey Kardashevskiy
2025-06-05 19:34 ` Kalra, Ashish
2025-05-19 23:57 ` [PATCH v4 3/5] crypto: ccp: Add support to enable CipherTextHiding on SNP_INIT_EX Ashish Kalra
2025-06-03 15:41 ` Tom Lendacky
2025-06-04 22:55 ` Kalra, Ashish
2025-06-05 6:32 ` Alexey Kardashevskiy
2025-06-05 19:09 ` Kalra, Ashish
2025-05-19 23:57 ` [PATCH v4 4/5] KVM: SEV: Introduce new min,max sev_es and sev_snp asid variables Ashish Kalra
2025-06-03 15:52 ` Tom Lendacky
2025-06-04 23:12 ` Kalra, Ashish
2025-05-20 0:02 ` [PATCH v4 5/5] KVM: SEV: Add SEV-SNP CipherTextHiding support Ashish Kalra
2025-05-23 17:29 ` Dave Hansen [this message]
2025-06-02 20:32 ` Kalra, Ashish
2025-06-03 16:26 ` Tom Lendacky
2025-06-05 0:17 ` Kalra, Ashish
2025-06-05 16:23 ` Tom Lendacky
2025-06-05 19:21 ` Kalra, Ashish
2025-06-05 6:32 ` Alexey Kardashevskiy
2025-06-05 19:18 ` Kalra, Ashish
2025-05-22 14:56 ` [PATCH v4 0/5] Add SEV-SNP CipherTextHiding feature support Kim Phillips
2025-05-27 20:47 ` Kalra, Ashish
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