This is a note to let you know that I've just added the patch titled
x86/xen: mark boot CPU of PV guest in MSR_IA32_APICBASE
to the 6.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-xen-mark-boot-cpu-of-pv-guest-in-msr_ia32_apicba.patch
and it can be found in the queue-6.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 46c21eeb719b96f822c7bef8acc35b326ac28ae9
Author: Juergen Gross <jgross@xxxxxxxx>
Date: Fri Oct 4 12:22:12 2024 +0200
x86/xen: mark boot CPU of PV guest in MSR_IA32_APICBASE
[ Upstream commit bf56c410162dbf2e27906acbdcd904cbbfdba302 ]
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@xxxxxxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 2c12ae42dc8bd..d6818c6cafda1 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;
