From: Mikhail Paulyshka <me@mixaill.net>
To: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/2] x86/rdrand: implement sanity check for RDSEED
Date: Fri, 14 Mar 2025 11:16:41 +0300 [thread overview]
Message-ID: <4aa902e5-24f8-4ae6-bc6b-485b7578fb27@mixaill.net> (raw)
In-Reply-To: <20250313173205.GIZ9MWlT9ElklGPSrD@fat_crate.local>
On 3/13/25 8:32 PM, Borislav Petkov wrote:
> On Wed, Mar 12, 2025 at 03:31:28PM +0300, Mikhail Paulyshka wrote:
>> On the AMD Cyan Skillfish (Family 0x17 Model 0x47 Stepping 0x0), which
>> is a Zen2-based APU found on the AMD BC-250 board, there is a situation
>> where RDRAND works fine, but RDSEED generates FF.
> On every read? Or only sometimes?
I didn't find a situation where it returns something different, so yes,
I believe it happens on every read and tested on 3+ hardware samples.
> Is CF clear when it returns FF?
Just right after rdseed %edx
# info registers edx
edx 0xffffffff -1
# info registers eflags
eflags 0x203 [ CF IF ]
next prev parent reply other threads:[~2025-03-14 8:16 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-12 12:31 Mikhail Paulyshka
2025-03-12 12:31 ` [PATCH 1/2] " Mikhail Paulyshka
2025-03-12 16:32 ` Borislav Petkov
2025-03-21 6:51 ` kernel test robot
2025-03-12 12:31 ` [PATCH 2/2] x86/rdrand: hide RDRAND and RDSEED from CPUID in case of a malfunction Mikhail Paulyshka
2025-03-12 12:45 ` Borislav Petkov
2025-03-12 13:36 ` Mikhail Paulyshka
2025-03-12 12:40 ` [PATCH 0/2] x86/rdrand: implement sanity check for RDSEED Borislav Petkov
2025-03-12 13:17 ` Mikhail Paulyshka
2025-03-14 8:40 ` Mikhail Paulyshka
2025-03-13 17:32 ` Borislav Petkov
2025-03-14 8:16 ` Mikhail Paulyshka [this message]
2025-03-18 20:50 ` Mario Limonciello
2025-03-18 21:40 ` Mikhail Paulyshka
2025-04-14 11:52 ` Borislav Petkov
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