From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH 2/2] x86, amd_ucode: Safeguard against #GP Date: Wed, 30 Jul 2014 17:29:40 +0100 Message-ID: <53D91D74.5080608@citrix.com> References: <1406736790-13283-1-git-send-email-aravind.gopalakrishnan@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1406736790-13283-1-git-send-email-aravind.gopalakrishnan@amd.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Aravind Gopalakrishnan , jbeulich@suse.com, keir@xen.org, boris.ostrovsky@oracle.com Cc: xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 30/07/14 17:13, Aravind Gopalakrishnan wrote: > 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 a2bdd20..57646c4 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);