* [PATCH] x86/xen: mark boot CPU of PV guest in MSR_IA32_APICBASE
@ 2024-10-07 10:42 Juergen Gross
0 siblings, 0 replies; only message in thread
From: Juergen Gross @ 2024-10-07 10:42 UTC (permalink / raw)
To: linux-kernel, x86
Cc: Juergen Gross, Boris Ostrovsky, Thomas Gleixner, Ingo Molnar,
Borislav Petkov, Dave Hansen, H. Peter Anvin, xen-devel,
Niels Dettenbach
Recent topology checks of the x86 boot code uncovered the need for
PV guests to have the boot cpu marked in the APICBASE MSR.
Fixes: 9d22c96316ac ("x86/topology: Handle bogus ACPI tables correctly")
Reported-by: Niels Dettenbach <nd@syndicat.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
arch/x86/xen/enlighten_pv.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 2c12ae42dc8b..d6818c6cafda 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -1032,6 +1032,10 @@ static u64 xen_do_read_msr(unsigned int msr, int *err)
switch (msr) {
case MSR_IA32_APICBASE:
val &= ~X2APIC_ENABLE;
+ if (smp_processor_id() == 0)
+ val |= MSR_IA32_APICBASE_BSP;
+ else
+ val &= ~MSR_IA32_APICBASE_BSP;
break;
}
return val;
--
2.43.0
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