From: Tom Lendacky <thomas.lendacky@amd.com>
To: Borislav Petkov <bp@alien8.de>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
linux-coco@lists.linux.dev, svsm-devel@coconut-svsm.dev,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Dan Williams <dan.j.williams@intel.com>,
Michael Roth <michael.roth@amd.com>,
Ashish Kalra <ashish.kalra@amd.com>
Subject: Re: [PATCH v3 02/14] x86/sev: Make the VMPL0 checking function more generic
Date: Wed, 17 Apr 2024 15:35:53 -0500 [thread overview]
Message-ID: <505dcf34-93ff-643c-b149-8ef9ce90c023@amd.com> (raw)
In-Reply-To: <20240417114658.GHZh-2sk47TZgCp4Mb@fat_crate.local>
On 4/17/24 06:46, Borislav Petkov wrote:
> On Mon, Mar 25, 2024 at 05:26:21PM -0500, Tom Lendacky wrote:
>> -static void enforce_vmpl0(void)
>> +static bool running_at_vmpl0(void *va)
>
> Not too crazy about it: you're turning it into a function which runs in
> boolean context but takes a void *?!
>
> And the boolean result is only a side-effect or what it does to the
> argument - modify its permissions. Which is weird and not really
> obvious.
Well, it doesn't really modify any permissions that matter. It tries to
change the permission of a lesser privileged VMPL level. Since the
kernel only runs at a single VMPL it would never be effected. The
operation performed here is to update VMPL1 permission levels (which can
only be done successfully at VMPL0) and return the result of the
operation. A success implies running at VMPL0 and failure implies not
running at VMPL0.
>
> I'd prefer it if you made it into
>
> static void vmpl0_modify_permissions(void *va)
I guess this confuses me, since it sounds like you're trying to modify
the VMPL0 permissions, which you can't do. Maybe calling it
modify_vmpl1_permissions() would be better. And a void return doesn't
tell me whether it was successful and, therefore, whether the kernel is
running at VMPL0.
Thanks,
Tom
>
> which basically says, modify the permissions of @va in vmpl0, which is
> a lot closer to what the function does.
>
> And then do
>
> #define running_at_vmpl0(va) vmpl0_modify_permissions((va))
>
> because then through the indirection is at least clear how that "am
> I running at VMPL0?" check is being done.
>
> And later, if we need other VMPLs, we can extend
> vmpl0_modify_permissions() and even do a more generic
>
> vmpl_modify_permissions(unsigned int vmpl_level, void *va)
>
> and so on and kill the silly macro.
>
> Thx.
>
next prev parent reply other threads:[~2024-04-17 20:36 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-25 22:26 [PATCH v3 00/14] Provide SEV-SNP support for running under an SVSM Tom Lendacky
2024-03-25 22:26 ` [PATCH v3 01/14] x86/sev: Rename snp_init() in the boot/compressed/sev.c file Tom Lendacky
2024-04-09 17:09 ` Borislav Petkov
2024-04-09 17:44 ` Tom Lendacky
2024-04-09 17:57 ` Borislav Petkov
2024-04-12 16:19 ` Gupta, Pankaj
2024-03-25 22:26 ` [PATCH v3 02/14] x86/sev: Make the VMPL0 checking function more generic Tom Lendacky
2024-04-12 16:41 ` Gupta, Pankaj
2024-04-17 11:46 ` Borislav Petkov
2024-04-17 20:35 ` Tom Lendacky [this message]
2024-04-17 20:50 ` Borislav Petkov
2024-04-18 18:38 ` Tom Lendacky
2024-04-21 7:12 ` Borislav Petkov
2024-03-25 22:26 ` [PATCH v3 03/14] x86/sev: Check for the presence of an SVSM in the SNP Secrets page Tom Lendacky
2024-04-12 17:03 ` Gupta, Pankaj
2024-04-17 20:40 ` Borislav Petkov
2024-04-18 21:17 ` Tom Lendacky
2024-04-22 22:07 ` Borislav Petkov
2024-03-25 22:26 ` [PATCH v3 04/14] x86/sev: Use kernel provided SVSM Calling Areas Tom Lendacky
2024-04-12 16:04 ` Gupta, Pankaj
2024-03-25 22:26 ` [PATCH v3 05/14] x86/sev: Perform PVALIDATE using the SVSM when not at VMPL0 Tom Lendacky
2024-03-25 22:26 ` [PATCH v3 06/14] x86/sev: Use the SVSM to create a vCPU when not in VMPL0 Tom Lendacky
2024-04-12 15:28 ` Gupta, Pankaj
2024-03-25 22:26 ` [PATCH v3 07/14] x86/sev: Provide SVSM discovery support Tom Lendacky
2024-04-15 16:12 ` Gupta, Pankaj
2024-03-25 22:26 ` [PATCH v3 08/14] x86/sev: Provide guest VMPL level to userspace Tom Lendacky
2024-03-25 22:26 ` [PATCH v3 09/14] virt: sev-guest: Choose the VMPCK key based on executing VMPL Tom Lendacky
2024-04-16 4:54 ` Dan Williams
2024-04-16 15:17 ` Tom Lendacky
2024-04-16 15:47 ` Dan Williams
2024-03-25 22:26 ` [PATCH v3 10/14] configfs-tsm: Allow the privlevel_floor attribute to be updated Tom Lendacky
2024-04-16 4:55 ` Dan Williams
2024-04-16 15:23 ` Tom Lendacky
2024-04-16 15:57 ` Dan Williams
2024-04-16 16:17 ` Tom Lendacky
2024-03-25 22:26 ` [PATCH v3 11/14] x86/sev: Extend the config-fs attestation support for an SVSM Tom Lendacky
2024-04-16 5:37 ` Dan Williams
2024-04-16 15:53 ` Tom Lendacky
2024-04-16 16:19 ` Dan Williams
2024-03-25 22:26 ` [PATCH v3 12/14] fs/configfs: Add a callback to determine attribute visibility Tom Lendacky
2024-04-16 5:46 ` Dan Williams
2024-04-16 16:01 ` Tom Lendacky
2024-04-16 18:25 ` Dan Williams
2024-04-16 19:54 ` Tom Lendacky
2024-04-16 20:03 ` Dan Williams
2024-03-25 22:26 ` [PATCH v3 13/14] x86/sev: Hide SVSM attestation entries if not running under an SVSM Tom Lendacky
2024-04-09 18:12 ` Kuppuswamy Sathyanarayanan
2024-04-12 15:52 ` Tom Lendacky
2024-04-15 19:16 ` Tom Lendacky
2024-04-15 19:48 ` Kuppuswamy Sathyanarayanan
2024-04-15 20:13 ` Tom Lendacky
2024-04-15 21:50 ` Kuppuswamy Sathyanarayanan
2024-04-15 22:03 ` Tom Lendacky
2024-04-16 6:09 ` Dan Williams
2024-04-16 6:08 ` Dan Williams
2024-04-16 6:05 ` Dan Williams
2024-04-16 5:47 ` Dan Williams
2024-04-16 16:07 ` Tom Lendacky
2024-04-16 6:03 ` Dan Williams
2024-04-16 16:10 ` Tom Lendacky
2024-03-25 22:26 ` [PATCH v3 14/14] x86/sev: Allow non-VMPL0 execution when an SVSM is present Tom Lendacky
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