From: "Limonciello, Mario" <mario.limonciello@amd.com>
To: Borislav Petkov <bp@alien8.de>
Cc: "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, Kees Cook <keescook@chromium.org>,
Thomas Lendacky <Thomas.Lendacky@amd.com>,
hughsient@gmail.com,
Martin Fernandez <martin.fernandez@eclypsium.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] x86/cpu: clear SME/SEV/SEV_ES features when not in use
Date: Fri, 11 Feb 2022 13:43:09 -0600 [thread overview]
Message-ID: <45d57d25-8fb3-fced-57f4-68680eb451e3@amd.com> (raw)
In-Reply-To: <YgYe1V0ViPYoB0az@zn.tnic>
On 2/11/2022 02:31, Borislav Petkov wrote:
> On Thu, Feb 10, 2022 at 11:36:52PM -0600, Mario Limonciello wrote:
>> Currently SME/SEV/SEV_ES features are reflective of whether the CPU
>> supports the features but not whether they have been activated by the
>> kernel.
>>
>> Change this around to clear the features if the kernel is not using
>> them so userspace can determine if they are available and in use
>> from `/proc/cpuinfo`.
>>
>> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
>> ---
>> arch/x86/kernel/cpu/amd.c | 8 ++++++++
>> 1 file changed, 8 insertions(+)
>>
>> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
>> index 4edb6f0f628c..4a7d4801fa0b 100644
>> --- a/arch/x86/kernel/cpu/amd.c
>> +++ b/arch/x86/kernel/cpu/amd.c
>> @@ -611,12 +611,20 @@ static void early_detect_mem_encrypt(struct cpuinfo_x86 *c)
>> if (!(msr & MSR_K7_HWCR_SMMLOCK))
>> goto clear_sev;
>>
>> + if (!cc_platform_has(CC_ATTR_MEM_ENCRYPT))
>> + goto clear_all;
>> + if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
>> + goto clear_sev;
>> + if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT))
>> + goto clear_sev_es;
>
> The cc_platform stuff is to be used in generic code - I think you can
> safely read MSR_AMD64_SEV here and look at the bits, just like the rest
> of this code does.
Yeah I was just looking to avoid the code duplication in multiple parts
of the kernel. If it's preferable to just duplicate the logic that
cc_platform_has here for the AMD platform, I'll do that instead.
>
> Also, why is this a separate patch? I.e., one single patch should be
> just fine.
Very well, will squash them.
next prev parent reply other threads:[~2022-02-11 19:43 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-11 5:36 [PATCH 1/2] x86: Use CPUID 0x8000001f to confirm SME availability Mario Limonciello
2022-02-11 5:36 ` [PATCH 2/2] x86/cpu: clear SME/SEV/SEV_ES features when not in use Mario Limonciello
2022-02-11 8:31 ` Borislav Petkov
2022-02-11 19:43 ` Limonciello, Mario [this message]
2022-02-11 14:46 ` Tom Lendacky
2022-02-11 19:54 ` Limonciello, Mario
2022-02-11 20:42 ` Tom Lendacky
2022-02-11 8:28 ` [PATCH 1/2] x86: Use CPUID 0x8000001f to confirm SME availability Borislav Petkov
2022-02-11 14:55 ` Tom Lendacky
2022-02-11 19:51 ` Limonciello, Mario
2022-02-11 21:09 ` Tom Lendacky
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=45d57d25-8fb3-fced-57f4-68680eb451e3@amd.com \
--to=mario.limonciello@amd.com \
--cc=Thomas.Lendacky@amd.com \
--cc=bp@alien8.de \
--cc=hughsient@gmail.com \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=martin.fernandez@eclypsium.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).