On 10/28/25 13:01, tip-bot2 for Gregory Price wrote:
The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: 607b9fb2ce248cc5b633c5949e0153838992c152 Gitweb:https://git.kernel.org/tip/607b9fb2ce248cc5b633c5949e0153838992c152 Author: Gregory Pricegourry@gourry.net AuthorDate: Mon, 20 Oct 2025 11:13:55 +02:00 Committer: Borislav Petkov (AMD)bp@alien8.de CommitterDate: Tue, 28 Oct 2025 12:37:49 +01:00
x86/CPU/AMD: Add RDSEED fix for Zen5
There's an issue with RDSEED's 16-bit and 32-bit register output variants on Zen5 which return a random value of 0 "at a rate inconsistent with randomness while incorrectly signaling success (CF=1)". Search the web for AMD-SB-7055 for more detail.
Add a fix glue which checks microcode revisions.
[ bp: Add microcode revisions checking, rewrite. ]
Cc:stable@vger.kernel.org Signed-off-by: Gregory Pricegourry@gourry.net Signed-off-by: Borislav Petkov (AMD)bp@alien8.de Link:https://lore.kernel.org/r/20251018024010.4112396-1-gourry@gourry.net
arch/x86/kernel/cpu/amd.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index ccaa51c..bc29be6 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -1035,8 +1035,18 @@ static void init_amd_zen4(struct cpuinfo_x86 *c) } } +static const struct x86_cpu_id zen5_rdseed_microcode[] = {
- ZEN_MODEL_STEP_UCODE(0x1a, 0x02, 0x1, 0x0b00215a),
- ZEN_MODEL_STEP_UCODE(0x1a, 0x11, 0x0, 0x0b101054),
+};
- static void init_amd_zen5(struct cpuinfo_x86 *c) {
- if (!x86_match_min_microcode_rev(zen5_rdseed_microcode)) {
clear_cpu_cap(c, X86_FEATURE_RDSEED);msr_clear_bit(MSR_AMD64_CPUID_FN_7, 18);pr_emerg_once("RDSEED32 is broken. Disabling the corresponding CPUID bit.\n");- } }
static void init_amd(struct cpuinfo_x86 *c)
Hi all,
This fix seems to break quite a bunch of users in CachyOS. There has been now several users reporting that there system can not get properly into the graphical interface.
CachyOS is compiling the packages with -march=znver5 and the GCC compiler currently does pass RDSEED.
This patch results into that also Client CPUs (Strix Point, Granite Ridge), can not execute this. There has been a microcode fix deployed in linux-firmware for Turin, but no other microcode changes seen yet.
I think it would be possible to exclude clients or providing a fix for this.
Example log:
Nov 03 13:37:33 hells drkonqi-coredump-processor[1073]: Incompatible processor. This Qt build requires the following features: Nov 03 13:37:33 hells drkonqi-coredump-processor[1073]: rdseed Nov 03 13:37:33 hells systemd-coredump[1077]: Process 1073 (drkonqi-coredum) of user 0 terminated abnormally with signal 6/ABRT, processing... Nov 03 13:37:33 hells systemd[1]: Started Process Core Dump (PID 1077/UID 0). Nov 03 13:37:33 hells systemd[1]: Started Pass systemd-coredump journal entries to relevant user for potential DrKonqi handling. Nov 03 13:37:33 hells drkonqi-coredump-processor[1079]: Incompatible processor. This Qt build requires the following features: Nov 03 13:37:33 hells drkonqi-coredump-processor[1079]: rdseed Nov 03 13:37:33 hells systemd-coredump[1082]: Process 1079 (drkonqi-coredum) of user 0 terminated abnormally with signal 6/ABRT, processing... Nov 03 13:37:33 hells systemd-coredump[1071]: Process 1049 (sddm) of user 0 dumped core.
Best regards,
Peter