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From: Borislav Petkov <bp@alien8.de>
To: Sean Christopherson <seanjc@google.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>, Pu Wen <puwen@hygon.cn>,
	Joerg Roedel <jroedel@suse.de>,
	x86@kernel.org, joro@8bytes.org, dave.hansen@linux.intel.com,
	peterz@infradead.org, tglx@linutronix.de, mingo@redhat.com,
	hpa@zytor.com, sashal@kernel.org, gregkh@linuxfoundation.org,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH] x86/sev: Check whether SEV or SME is supported first
Date: Tue, 1 Jun 2021 19:48:40 +0200	[thread overview]
Message-ID: <YLZy+JR7TNEeNA6C@zn.tnic> (raw)
In-Reply-To: <YLZrXEQ8w5ntu7ov@google.com>

On Tue, Jun 01, 2021 at 05:16:12PM +0000, Sean Christopherson wrote:
> The bug isn't limited to out-of-spec hardware.  At the point of #GP, sme_enable()
> has only verified the max leaf is greater than 0x8000001f, it has not verified
> that 0x8000001f is actually supported.  The APM itself declares several leafs
> between 0x80000000 and 0x8000001f as reserved/unsupported, so we can't argue that
> 0x8000001f must be supported if the max leaf is greater than 0x8000001f.

If a hypervisor says that 0x8000001f is supported but then we explode
when reading MSR_AMD64_SEV, then hypervisor gets to keep both pieces.

We're not going to workaround all possible insane hardware/hypervisor
configurations just because they dropped the ball.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

  reply	other threads:[~2021-06-01 17:48 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-26  7:24 [PATCH] x86/sev: Check whether SEV or SME is supported first Pu Wen
2021-05-26 17:27 ` Sean Christopherson
2021-05-27 15:08   ` Pu Wen
2021-05-31  9:37     ` Joerg Roedel
2021-05-31 14:56       ` Pu Wen
2021-06-01 14:39         ` Borislav Petkov
2021-06-01 16:14           ` Sean Christopherson
2021-06-01 16:36             ` Tom Lendacky
2021-06-01 16:59               ` Borislav Petkov
2021-06-01 17:16                 ` Sean Christopherson
2021-06-01 17:48                   ` Borislav Petkov [this message]
2021-06-01 18:08                     ` Sean Christopherson
2021-06-01 18:24                       ` Borislav Petkov
2021-06-01 17:09               ` Sean Christopherson
2021-06-01 18:30 ` Tom Lendacky
2021-06-02  6:55   ` Wen Pu

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