From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH] KEXEC: disable hpet legacy broadcasts earlier Date: Thu, 18 Aug 2011 14:48:15 +0100 Message-ID: <4E4D181F.4070706@citrix.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: "xen-devel@lists.xensource.com >> \"xen-devel@lists.xensource.com\"" List-Id: xen-devel@lists.xenproject.org On 18/08/11 14:47, Keir Fraser wrote: > On 18/08/2011 14:31, "Andrew Cooper" wrote: > >> On x2apic machines which booted in xapic mode, >> hpet_disable_legacy_broadcast() sends an event check IPI to all online >> processors. This leads to a protection fault as the genapic blindly >> pokes x2apic MSRs while the local apic is in xapic mode. >> >> One option is to change genapic when we shut down the local apic, but >> there are still problems with trying to IPI processors in the online >> processor map which are actually sitting in NMI loops >> >> Another option is to have each CPU take itself out of the online CPU >> map during the NMI shootdown. >> >> Realistically however, disabling hpet legacy broadcasts earlier in the >> kexec path is the easiest fix to the problem. > This for 4.1.2 as well I guess? Yes please ~Andrew >> Signed-off-by: Andrew Cooper >> >> diff -r fc2be6cb89ad -r dcb3ed7b7dbd xen/arch/x86/crash.c >> --- a/xen/arch/x86/crash.c Tue Aug 16 15:05:55 2011 +0100 >> +++ b/xen/arch/x86/crash.c Thu Aug 18 14:30:32 2011 +0100 >> @@ -29,6 +29,7 @@ >> #include >> #include >> #include >> +#include >> >> static atomic_t waiting_for_crash_ipi; >> static unsigned int crashing_cpu; >> @@ -61,6 +62,9 @@ static void nmi_shootdown_cpus(void) >> >> local_irq_disable(); >> >> + if ( hpet_broadcast_is_available() ) >> + hpet_disable_legacy_broadcast(); >> + >> crashing_cpu = smp_processor_id(); >> local_irq_count(crashing_cpu) = 0; >> >> diff -r fc2be6cb89ad -r dcb3ed7b7dbd xen/arch/x86/machine_kexec.c >> --- a/xen/arch/x86/machine_kexec.c Tue Aug 16 15:05:55 2011 +0100 >> +++ b/xen/arch/x86/machine_kexec.c Thu Aug 18 14:30:32 2011 +0100 >> @@ -85,9 +85,6 @@ void machine_kexec(xen_kexec_image_t *im >> .limit = LAST_RESERVED_GDT_BYTE >> }; >> >> - if ( hpet_broadcast_is_available() ) >> - hpet_disable_legacy_broadcast(); >> - >> /* We are about to permenantly jump out of the Xen context into the kexec >> * purgatory code. We really dont want to be still servicing interupts. >> */ >> >> _______________________________________________ >> Xen-devel mailing list >> Xen-devel@lists.xensource.com >> http://lists.xensource.com/xen-devel > -- Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer T: +44 (0)1223 225 900, http://www.citrix.com