From 0399f73299f1b7e04de329050f7111b362b7eeb5 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Mon, 12 Oct 2015 11:22:42 +0200 Subject: x86/microcode/amd: Do not overwrite final patch levels MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit A certain number of patch levels of applied microcode should not be overwritten by the microcode loader, otherwise bad things will happen. Check those and abort update if the current core has one of those final patch levels applied by the BIOS. 32-bit needs special handling, of course. See https://bugzilla.suse.com/show_bug.cgi?id=913996 for more info. Tested-by: Peter Kirchgeßner Signed-off-by: Borislav Petkov Cc: Borislav Petkov Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Tony Luck Link: http://lkml.kernel.org/r/1444641762-9437-7-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/microcode/amd.c | 38 ++++++++++++++++++++++++++++++++----- 1 file changed, 33 insertions(+), 5 deletions(-) (limited to 'arch/x86/kernel/cpu/microcode/amd.c') diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c index 2d630138bf3e..da922d1e2f71 100644 --- a/arch/x86/kernel/cpu/microcode/amd.c +++ b/arch/x86/kernel/cpu/microcode/amd.c @@ -177,6 +177,16 @@ static unsigned int verify_patch_size(u8 family, u32 patch_size, return patch_size; } +/* + * Those patch levels cannot be updated to newer ones and thus should be final. + */ +static u32 final_levels[] = { + 0x01000098, + 0x0100009f, + 0x010000af, + 0, /* T-101 terminator */ +}; + /* * Check the current patch level on this CPU. * @@ -187,13 +197,31 @@ static unsigned int verify_patch_size(u8 family, u32 patch_size, * - true: if update should stop * - false: otherwise */ -bool check_current_patch_level(u32 *rev) +bool check_current_patch_level(u32 *rev, bool early) { - u32 dummy; + u32 lvl, dummy, i; + bool ret = false; + u32 *levels; + + native_rdmsr(MSR_AMD64_PATCH_LEVEL, lvl, dummy); + + if (IS_ENABLED(CONFIG_X86_32) && early) + levels = (u32 *)__pa_nodebug(&final_levels); + else + levels = final_levels; + + for (i = 0; levels[i]; i++) { + if (lvl == levels[i]) { + lvl = 0; + ret = true; + break; + } + } - native_rdmsr(MSR_AMD64_PATCH_LEVEL, *rev, dummy); + if (rev) + *rev = lvl; - return false; + return ret; } int __apply_microcode_amd(struct microcode_amd *mc_amd) @@ -229,7 +257,7 @@ int apply_microcode_amd(int cpu) mc_amd = p->data; uci->mc = p->data; - if (check_current_patch_level(&rev)) + if (check_current_patch_level(&rev, false)) return -1; /* need to apply patch? */ -- cgit v1.2.3