From 8b24b07eef3ba13ce48d800f28c1c28de5a2b4a7 Mon Sep 17 00:00:00 2001 From: Aravind Gopalakrishnan Date: Fri, 1 Aug 2014 16:48:30 +0200 Subject: [PATCH] x86, amd_ucode: safeguard against #GP When HW tries to load a corrupted patch, it generates #GP and depending on 'noreboot' parameter on grub, the system is either stuck in a reboot loop or is hung. Use wrmsr_safe instead of wrmsrl so that we fail to load microcode gracefully. Signed-off-by: Aravind Gopalakrishnan Reviewed-by: Boris Ostrovsky Reviewed-by: Andrew Cooper --- xen/arch/x86/microcode_amd.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/xen/arch/x86/microcode_amd.c b/xen/arch/x86/microcode_amd.c index 1e5503dce7..b68cf93731 100644 --- a/xen/arch/x86/microcode_amd.c +++ b/xen/arch/x86/microcode_amd.c @@ -193,6 +193,7 @@ static int apply_microcode(int cpu) uint32_t rev; struct microcode_amd *mc_amd = uci->mc.mc_amd; struct microcode_header_amd *hdr; + int hw_err; /* We should bind the task to the CPU */ BUG_ON(raw_smp_processor_id() != cpu); @@ -206,7 +207,7 @@ static int apply_microcode(int cpu) spin_lock_irqsave(µcode_update_lock, flags); - wrmsrl(MSR_AMD_PATCHLOADER, (unsigned long)hdr); + hw_err = wrmsr_safe(MSR_AMD_PATCHLOADER, (unsigned long)hdr); /* get patch id after patching */ rdmsrl(MSR_AMD_PATCHLEVEL, rev); @@ -214,7 +215,7 @@ static int apply_microcode(int cpu) spin_unlock_irqrestore(µcode_update_lock, flags); /* check current patch id and patch's id for match */ - if ( rev != hdr->patch_id ) + if ( hw_err || (rev != hdr->patch_id) ) { printk(KERN_ERR "microcode: CPU%d update from revision " "%#x to %#x failed\n", cpu, rev, hdr->patch_id); -- 2.30.2