From: Borislav Petkov <bp@alien8.de>
To: Tom Lendacky <thomas.lendacky@amd.com>
Cc: "Limonciello, Mario" <mario.limonciello@amd.com>,
Martin Fernandez <martin.fernandez@eclypsium.com>,
linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org,
platform-driver-x86@vger.kernel.org, linux-mm@kvack.org,
tglx@linutronix.de, mingo@redhat.com,
dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
ardb@kernel.org, dvhart@infradead.org, andy@infradead.org,
gregkh@linuxfoundation.org, rafael@kernel.org, rppt@kernel.org,
akpm@linux-foundation.org, daniel.gutson@eclypsium.com,
hughsient@gmail.com, alex.bazhaniuk@eclypsium.com,
alison.schofield@intel.com, keescook@chromium.org
Subject: Re: [PATCH v6 6/6] drivers/node: Show in sysfs node's crypto capabilities
Date: Fri, 4 Feb 2022 19:00:49 +0100 [thread overview]
Message-ID: <Yf1p0ZjPf9Qaqwtg@zn.tnic> (raw)
In-Reply-To: <5ee34cad-8daf-6282-f2ed-cbc92a89d013@amd.com>
On Fri, Feb 04, 2022 at 11:12:04AM -0600, Tom Lendacky wrote:
> https://elixir.bootlin.com/linux/latest/source/arch/x86/kernel/process.c#L761
For those who won't open a browser just to see what he means :), that's
this snippet:
void stop_this_cpu(void *dummy):
/*
* Use wbinvd on processors that support SME. This provides support
* for performing a successful kexec when going from SME inactive
* to SME active (or vice-versa). The cache must be cleared so that
* if there are entries with the same physical address, both with and
* without the encryption bit, they don't race each other when flushed
* and potentially end up with the wrong entry being committed to
* memory.
*/
if (boot_cpu_has(X86_FEATURE_SME))
native_wbinvd();
Well, we do clear our *representation* of CPUID flags for other features
- see output of
$ git grep -E "(setup_)?clear_cpu_cap"
for examples. We do that for SME even: early_detect_mem_encrypt().
Which means, since this needs to be "processors that support SME", this
line should change to:
/* ... test the CPUID bit directly because the machine might've cleared
* X86_FEATURE_SME due to cmdline options.
*/
if (cpuid_eax(0x8000001f) & BIT(0))
native_wbinvd();
I'd say...
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2022-02-04 18:01 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-03 16:43 [PATCH v6 0/6] x86: Show in sysfs if a memory node is able to do encryption Martin Fernandez
2022-02-03 16:43 ` [PATCH v6 1/6] mm/memblock: Tag memblocks with crypto capabilities Martin Fernandez
2022-02-03 18:07 ` Mike Rapoport
2022-02-03 18:24 ` Martin Fernandez
2022-02-07 21:18 ` Kees Cook
2022-02-08 14:39 ` Martin Fernandez
2022-02-03 16:43 ` [PATCH v6 2/6] mm/mmzone: Tag pg_data_t " Martin Fernandez
2022-02-07 21:19 ` Kees Cook
2022-02-03 16:43 ` [PATCH v6 3/6] x86/e820: Refactor range_update and range_remove Martin Fernandez
2022-02-07 21:45 ` Kees Cook
2022-02-08 8:40 ` Mike Rapoport
2022-02-08 21:01 ` Martin Fernandez
2022-02-15 7:10 ` Mike Rapoport
2022-02-15 14:14 ` Martin Fernandez
2022-02-08 21:09 ` Martin Fernandez
2022-03-04 20:32 ` Martin Fernandez
2022-02-08 21:04 ` Daniel Gutson
2022-02-03 16:43 ` [PATCH v6 4/6] x86/e820: Tag e820_entry with crypto capabilities Martin Fernandez
2022-02-07 21:56 ` Kees Cook
2022-02-08 14:46 ` Martin Fernandez
2022-02-03 16:43 ` [PATCH v6 5/6] x86/efi: Tag e820_entries as crypto capable from EFI memmap Martin Fernandez
2022-02-03 16:43 ` [PATCH v6 6/6] drivers/node: Show in sysfs node's crypto capabilities Martin Fernandez
2022-02-04 3:47 ` Limonciello, Mario
2022-02-04 13:21 ` Martin Fernandez
2022-02-04 15:59 ` Tom Lendacky
2022-02-04 16:23 ` Limonciello, Mario
2022-02-04 16:28 ` Borislav Petkov
2022-02-04 17:12 ` Tom Lendacky
2022-02-04 17:49 ` Limonciello, Mario
2022-02-04 18:00 ` Borislav Petkov [this message]
2022-02-04 18:49 ` Tom Lendacky
2022-02-04 21:49 ` Borislav Petkov
2022-02-07 3:39 ` Kees Cook
2022-02-07 10:02 ` Borislav Petkov
2022-02-04 4:56 ` Mike Rapoport
2022-02-04 12:27 ` Martin Fernandez
2022-02-04 13:37 ` Mike Rapoport
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