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From: "Chang S. Bae" <chang.seok.bae@intel.com>
To: Chao Gao <chao.gao@intel.com>
Cc: <x86@kernel.org>, <linux-kernel@vger.kernel.org>,
	<kvm@vger.kernel.org>, <tglx@linutronix.de>,
	<dave.hansen@intel.com>, <seanjc@google.com>,
	<pbonzini@redhat.com>, <peterz@infradead.org>,
	<rick.p.edgecombe@intel.com>, <weijiang.yang@intel.com>,
	<john.allen@amd.com>, <bp@alien8.de>, <xin3.li@intel.com>,
	Ingo Molnar <mingo@redhat.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"Aruna Ramakrishna" <aruna.ramakrishna@oracle.com>,
	Mitchell Levy <levymitchell0@gmail.com>,
	Adamos Ttofari <attofari@amazon.de>,
	Uros Bizjak <ubizjak@gmail.com>
Subject: Re: [PATCH v4 8/8] x86/fpu/xstate: Warn if guest-only supervisor states are detected in normal fpstate
Date: Thu, 3 Apr 2025 17:02:05 -0700	[thread overview]
Message-ID: <fe730028-1861-4fc3-8ddb-6b218d5aa234@intel.com> (raw)
In-Reply-To: <Z+1KBN+s3CWdTN60@intel.com>

On 4/2/2025 7:30 AM, Chao Gao wrote:
> 
> The goal is to ensure that guest-only _supervisor_ features are not enabled in
> non-guest FPUs.

I think the common XSAVE path matters here. The other XSAVE paths — 
signal delivery and saving the LBR state — already handle supervisor 
states properly. Signal delivery excludes all of supervisor states from 
the RFBM, while LBR state saving triggers a warning if any non-LBR state 
is set in the RFBM. Given this, the guard seems good enough unless 
missing something.

Thanks,
Chang

  reply	other threads:[~2025-04-04  0:02 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-03-18 15:31 [PATCH v4 0/8] Introduce CET supervisor state support Chao Gao
2025-03-18 15:31 ` [PATCH v4 1/8] x86/fpu/xstate: Always preserve non-user xfeatures/flags in __state_perm Chao Gao
2025-04-01 17:17   ` Chang S. Bae
2025-04-01 17:56     ` Sean Christopherson
2025-03-18 15:31 ` [PATCH v4 2/8] x86/fpu: Drop @perm from guest pseudo FPU container Chao Gao
2025-04-01 17:16   ` Chang S. Bae
2025-04-02  1:56     ` Chao Gao
2025-03-18 15:31 ` [PATCH v4 3/8] x86/fpu/xstate: Add CET supervisor xfeature support Chao Gao
2025-04-01 17:15   ` Chang S. Bae
2025-04-02  2:28     ` Chao Gao
2025-04-02 21:37     ` Dave Hansen
2025-04-03 13:26       ` Chao Gao
2025-04-03 14:04       ` Ingo Molnar
2025-03-18 15:31 ` [PATCH v4 4/8] x86/fpu/xstate: Differentiate default features for host and guest FPUs Chao Gao
2025-04-01 17:18   ` Chang S. Bae
2025-04-02  3:16     ` Chao Gao
2025-03-18 15:31 ` [PATCH v4 5/8] x86/fpu: Initialize guest FPU permissions from guest defaults Chao Gao
2025-03-18 15:31 ` [PATCH v4 6/8] x86/fpu: Initialize guest fpstate and FPU pseudo container " Chao Gao
2025-03-18 15:31 ` [PATCH v4 7/8] x86/fpu/xstate: Introduce "guest-only" supervisor xfeature set Chao Gao
2025-04-01 17:16   ` Chang S. Bae
2025-04-02  4:29     ` Chao Gao
2025-03-18 15:31 ` [PATCH v4 8/8] x86/fpu/xstate: Warn if guest-only supervisor states are detected in normal fpstate Chao Gao
2025-04-01 17:17   ` Chang S. Bae
2025-04-02 14:30     ` Chao Gao
2025-04-04  0:02       ` Chang S. Bae [this message]
2025-04-04  1:06         ` Dave Hansen
2025-04-01 17:20 ` [PATCH v4 0/8] Introduce CET supervisor state support Chang S. Bae
2025-04-02 21:12 ` Edgecombe, Rick P
2025-04-02 21:35   ` Dave Hansen
2025-04-02 21:44     ` Sean Christopherson

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