linux-kernel - Re: [PATCH v3 3/8] x86/sev: Require the RMPREAD instruction after Fam19h

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <89641965-5f0d-c5da-2399-13b18669ea85@amd.com>
Date: Fri, 18 Oct 2024 08:30:27 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: Neeraj Upadhyay <Neeraj.Upadhyay@....com>, linux-kernel@...r.kernel.org,
 x86@...nel.org
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 Michael Roth <michael.roth@....com>, Ashish Kalra <ashish.kalra@....com>
Subject: Re: [PATCH v3 3/8] x86/sev: Require the RMPREAD instruction after
 Fam19h



On 10/17/24 23:26, Neeraj Upadhyay wrote:
> 
> 
> On 9/30/2024 8:52 PM, Tom Lendacky wrote:
>> Limit usage of the non-architectural RMP format to Fam19h processors.
>> The RMPREAD instruction, with its architecture defined output, is
>> available, and should be used, for RMP access beyond Fam19h.
>>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
>> ---
>>  arch/x86/kernel/cpu/amd.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
>> index 015971adadfc..ddbb6dd75fb2 100644
>> --- a/arch/x86/kernel/cpu/amd.c
>> +++ b/arch/x86/kernel/cpu/amd.c
>> @@ -358,7 +358,8 @@ static void bsp_determine_snp(struct cpuinfo_x86 *c)
>>  		 * for which the RMP table entry format is currently defined for.
>>  		 */
>>  		if (!cpu_has(c, X86_FEATURE_HYPERVISOR) &&
>> -		    c->x86 >= 0x19 && snp_probe_rmptable_info()) {
>> +		    (c->x86 == 0x19 || cpu_feature_enabled(X86_FEATURE_RMPREAD)) &&
> 
> Maybe update the comment above this if condition with information about RMPREAD FEAT?

Yep.

Thanks,
Tom

> 
> 
> - Neeraj
> 
>> +		    snp_probe_rmptable_info()) {
>>  			cc_platform_set(CC_ATTR_HOST_SEV_SNP);
>>  		} else {
>>  			setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);