mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-25 01:21:01 +07:00
c49a0a8013
There have been reports of RDRAND issues after resuming from suspend on some AMD family 15h and family 16h systems. This issue stems from a BIOS not performing the proper steps during resume to ensure RDRAND continues to function properly. RDRAND support is indicated by CPUID Fn00000001_ECX[30]. This bit can be reset by clearing MSR C001_1004[62]. Any software that checks for RDRAND support using CPUID, including the kernel, will believe that RDRAND is not supported. Update the CPU initialization to clear the RDRAND CPUID bit for any family 15h and 16h processor that supports RDRAND. If it is known that the family 15h or family 16h system does not have an RDRAND resume issue or that the system will not be placed in suspend, the "rdrand=force" kernel parameter can be used to stop the clearing of the RDRAND CPUID bit. Additionally, update the suspend and resume path to save and restore the MSR C001_1004 value to ensure that the RDRAND CPUID setting remains in place after resuming from suspend. Note, that clearing the RDRAND CPUID bit does not prevent a processor that normally supports the RDRAND instruction from executing it. So any code that determined the support based on family and model won't #UD. Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Andrew Cooper <andrew.cooper3@citrix.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chen Yu <yu.c.chen@intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Kees Cook <keescook@chromium.org> Cc: "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org> Cc: "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org> Cc: Nathan Chancellor <natechancellor@gmail.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: <stable@vger.kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "x86@kernel.org" <x86@kernel.org> Link: https://lkml.kernel.org/r/7543af91666f491547bd86cebb1e17c66824ab9f.1566229943.git.thomas.lendacky@amd.com |
||
|---|---|---|
| .. | ||
| cpu.c | ||
| hibernate_32.c | ||
| hibernate_64.c | ||
| hibernate_asm_32.S | ||
| hibernate_asm_64.S | ||
| hibernate.c | ||
| Makefile | ||