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From: Andi Kleen <ak@linux.intel.com>
To: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	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>,
	Peter Zijlstra <peterz@infradead.org>,
	Josh Poimboeuf <jpoimboe@kernel.org>,
	Andy Lutomirski <luto@kernel.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	tony.luck@intel.com, tim.c.chen@linux.intel.com,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
	kvm@vger.kernel.org,
	Alyssa Milburn <alyssa.milburn@linux.intel.com>,
	Daniel Sneddon <daniel.sneddon@linux.intel.com>,
	antonio.gomez.iglesias@linux.intel.com
Subject: Re: [PATCH  3/6] x86/entry_32: Add VERW just before userspace transition
Date: Fri, 20 Oct 2023 16:49:34 -0700	[thread overview]
Message-ID: <ZTMSDkBzUZBiTBoG@tassilo> (raw)
In-Reply-To: <20231020-delay-verw-v1-3-cff54096326d@linux.intel.com>

On Fri, Oct 20, 2023 at 01:45:09PM -0700, Pawan Gupta wrote:
> As done for entry_64, add support for executing VERW late in exit to
> user path for 32-bit mode.
> 
> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
> ---
>  arch/x86/entry/entry_32.S | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
> index 6e6af42e044a..bbf77d2aab2e 100644
> --- a/arch/x86/entry/entry_32.S
> +++ b/arch/x86/entry/entry_32.S
> @@ -886,6 +886,9 @@ SYM_FUNC_START(entry_SYSENTER_32)
>  	popfl
>  	popl	%eax
>  
> +	/* Mitigate CPU data sampling attacks .e.g. MDS */
> +	USER_CLEAR_CPU_BUFFERS
> +
>  	/*
>  	 * Return back to the vDSO, which will pop ecx and edx.
>  	 * Don't bother with DS and ES (they already contain __USER_DS).

Did you forget the INT 0x80 entry point?

-Andi


  reply	other threads:[~2023-10-20 23:50 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-20 20:44 [PATCH 0/6] Delay VERW Pawan Gupta
2023-10-20 20:44 ` [PATCH 1/6] x86/bugs: Add asm helpers for executing VERW Pawan Gupta
2023-10-20 23:13   ` Sean Christopherson
2023-10-21  1:00     ` Pawan Gupta
2023-10-20 23:55   ` [RESEND][PATCH " Andrew Cooper
2023-10-21  1:18     ` Pawan Gupta
2023-10-21  1:33       ` Andrew Cooper
2023-10-21  2:21         ` Pawan Gupta
2023-10-23 18:08           ` Josh Poimboeuf
2023-10-23 19:09             ` Pawan Gupta
2023-10-25  6:28     ` Pawan Gupta
2023-10-25  7:22       ` Peter Zijlstra
2023-10-25  7:52         ` Andrew Cooper
2023-10-25  8:02           ` Peter Zijlstra
2023-10-25 15:27         ` Pawan Gupta
     [not found]   ` <6439a094-23a6-4de3-aa41-bd033163e044@citrix.com>
2023-10-22 16:16     ` [PATCH " Peter Zijlstra
2023-10-20 20:45 ` [PATCH 2/6] x86/entry_64: Add VERW just before userspace transition Pawan Gupta
2023-10-23 18:22   ` Josh Poimboeuf
2023-10-23 19:13     ` Pawan Gupta
2023-10-23 19:17     ` Dave Hansen
2023-10-23 18:35   ` Josh Poimboeuf
2023-10-23 21:04     ` Pawan Gupta
2023-10-23 21:47       ` Josh Poimboeuf
2023-10-23 22:30         ` Pawan Gupta
2023-10-23 22:45           ` Dave Hansen
2023-10-24  0:00             ` Pawan Gupta
2023-10-20 20:45 ` [PATCH 3/6] x86/entry_32: " Pawan Gupta
2023-10-20 23:49   ` Andi Kleen [this message]
2023-10-21  1:28     ` Pawan Gupta
2023-10-20 20:45 ` [PATCH 4/6] x86/bugs: Use ALTERNATIVE() instead of mds_user_clear static key Pawan Gupta
2023-10-23 18:48   ` Josh Poimboeuf
2023-10-23 21:09     ` Pawan Gupta
2023-10-20 20:45 ` [PATCH 5/6] x86/bugs: Cleanup mds_user_clear Pawan Gupta
2023-10-23  8:51   ` Nikolay Borisov
2023-10-23 16:06     ` Pawan Gupta
2023-10-20 20:45 ` [PATCH 6/6] KVM: VMX: Move VERW closer to VMentry for MDS mitigation Pawan Gupta
2023-10-20 22:55   ` Sean Christopherson
2023-10-21  0:46     ` Pawan Gupta
2023-10-23 14:58       ` Sean Christopherson
2023-10-23 17:05         ` Pawan Gupta
2023-10-23 18:56   ` Josh Poimboeuf
2023-10-23 21:17     ` Pawan Gupta

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