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From: Tom Lendacky <thomas.lendacky@amd.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>,
	the arch/x86 maintainers <x86@kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Andy Lutomirski <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Dave Young <dyoung@redhat.com>,
	Brijesh Singh <brijesh.singh@amd.com>,
	Kexec Mailing List <kexec@lists.infradead.org>
Subject: Re: [PATCH v1 1/2] x86/mm, kexec: Fix memory corruption with SME on successive kexecs
Date: Thu, 27 Jul 2017 13:47:42 -0500	[thread overview]
Message-ID: <a052ad5b-cb70-7279-6837-0cc6e7f8a19c@amd.com> (raw)
In-Reply-To: <CA+55aFwRykCYz0p1WTJeehcpXwqN10UGOJrMcTRB4zUxt=D5ng@mail.gmail.com>

On 7/27/2017 12:34 PM, Linus Torvalds wrote:
> On Thu, Jul 27, 2017 at 7:15 AM, Tom Lendacky <thomas.lendacky@amd.com> wrote:
>>
>> I can #ifdef the wbinvd based on whether AMD_MEM_ENCRYPT is configured
>> or not so that the wbinvd is avoided if not configured.
> 
> I suspect an ifdef will be useless, since things like distro kernels
> tend to enable everything.
> 
> So it should probably be disabled dynamically, and only done if the
> AMD memory encryption thing has actually been active.
> 
> [ There have also been various actual errata with wbinvd, so there
> tends to be a non-performance reason to try to avoid it unless
> strictly required ]

Ok, I'll make the wbinvd a run time decision based on whether SME is
active at the time.

Thanks,
Tom

> 
>                 Linus
> 

WARNING: multiple messages have this Message-ID (diff)
From: Tom Lendacky <thomas.lendacky@amd.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Brijesh Singh <brijesh.singh@amd.com>,
	the arch/x86 maintainers <x86@kernel.org>,
	Kexec Mailing List <kexec@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Andy Lutomirski <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Dave Young <dyoung@redhat.com>, Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH v1 1/2] x86/mm, kexec: Fix memory corruption with SME on successive kexecs
Date: Thu, 27 Jul 2017 13:47:42 -0500	[thread overview]
Message-ID: <a052ad5b-cb70-7279-6837-0cc6e7f8a19c@amd.com> (raw)
In-Reply-To: <CA+55aFwRykCYz0p1WTJeehcpXwqN10UGOJrMcTRB4zUxt=D5ng@mail.gmail.com>

On 7/27/2017 12:34 PM, Linus Torvalds wrote:
> On Thu, Jul 27, 2017 at 7:15 AM, Tom Lendacky <thomas.lendacky@amd.com> wrote:
>>
>> I can #ifdef the wbinvd based on whether AMD_MEM_ENCRYPT is configured
>> or not so that the wbinvd is avoided if not configured.
> 
> I suspect an ifdef will be useless, since things like distro kernels
> tend to enable everything.
> 
> So it should probably be disabled dynamically, and only done if the
> AMD memory encryption thing has actually been active.
> 
> [ There have also been various actual errata with wbinvd, so there
> tends to be a non-performance reason to try to avoid it unless
> strictly required ]

Ok, I'll make the wbinvd a run time decision based on whether SME is
active at the time.

Thanks,
Tom

> 
>                 Linus
> 

_______________________________________________
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kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

  reply	other threads:[~2017-07-27 18:47 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-26 18:04 [PATCH v1 0/2] x86: Secure Memory Encryption (SME) fixes 2017-07-26 Tom Lendacky
2017-07-26 18:04 ` Tom Lendacky
2017-07-26 18:04 ` [PATCH v1 1/2] x86/mm, kexec: Fix memory corruption with SME on successive kexecs Tom Lendacky
2017-07-26 18:04   ` Tom Lendacky
2017-07-27  7:17   ` Ingo Molnar
2017-07-27  7:17     ` Ingo Molnar
2017-07-27 14:15     ` Tom Lendacky
2017-07-27 14:15       ` Tom Lendacky
2017-07-27 17:34       ` Linus Torvalds
2017-07-27 17:34         ` Linus Torvalds
2017-07-27 18:47         ` Tom Lendacky [this message]
2017-07-27 18:47           ` Tom Lendacky
2017-07-26 18:04 ` [PATCH v1 2/2] acpi, x86: Remove encryption mask from ACPI page protection type Tom Lendacky
2017-07-27  7:39   ` Ingo Molnar
2017-07-27 14:53     ` Tom Lendacky
2017-07-27 14:41   ` Borislav Petkov
2017-07-27 14:57     ` Tom Lendacky
2017-07-28  6:28       ` Ingo Molnar

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