From 2d48fb9ddca0aa6510f4f18966112222d405aedc Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Fri, 4 Oct 2024 12:22:12 +0200 Subject: [PATCH] x86/xen: mark boot CPU of PV guest in MSR_IA32_APICBASE 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 Signed-off-by: Juergen Gross --- 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