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Re: [Xen-devel] [PATCH] x86/amd: Fix xen_apic_write warnings in Dom0
On 10/15/2012 02:09 PM, Keir Fraser wrote:
On 15/10/2012 12:12, "Jan Beulich"<JBeulich@xxxxxxxx> wrote:
On 09.10.12 at 10:06, Wei Wang<wei.wang2@xxxxxxx> wrote:
--- a/xen/arch/x86/cpu/amd.c
+++ b/xen/arch/x86/cpu/amd.c
@@ -485,6 +485,17 @@ static void __devinit init_amd(struct cpuinfo_x86 *c)
if (c->x86> 0x11)
set_bit(X86_FEATURE_ARAT, c->x86_capability);
+ /*
+ * Prior to Family 0x14, perf counters are not reset during warm reboot.
+ * We have to reset them manually.
+ */
+ if (c->x86< 0x14) {
+ wrmsrl(MSR_K7_PERFCTR0, 0);
+ wrmsrl(MSR_K7_PERFCTR1, 0);
+ wrmsrl(MSR_K7_PERFCTR2, 0);
+ wrmsrl(MSR_K7_PERFCTR3, 0);
+ }
This collides with the NMI watchdog setup: smp_callin() calls
setup_local_APIC() _before_ calling smp_store_cpu_info(), and
hence you write zero again to an MSR possibly already in use.
Since setup_k7_watchdog() itself does the clearing of the MSRs
in question already, I would think that the most simple
adjustment to your patch would be to make the condition
if (nmi_watchdog != NMI_LOCAL_APIC&& c->x86< 0x14) {
If you agree (and Keir doesn't object), I would commit it that way.
Sounds good.
Acked-by: Keir Fraser<keir@xxxxxxx>
Sounds good to me too. Acked
Thanks,
Wei
Jan
+
if (cpuid_edx(0x80000007)& (1<< 10)) {
rdmsr(MSR_K7_HWCR, l, h);
l |= (1<< 27); /* Enable read-only APERF/MPERF bit */
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