Commit f094a39c authored Jan 17, 2022 by Christian Borntraeger Committed by Heiko Carstens Jan 23, 2022

s390/nmi: handle vector validity failures for KVM guests



The machine check validity bit tells about the context. If a KVM guest
was running the bit tells about the guest validity and the host state is
not affected. As a guest can disable the guest validity this might
result in unwanted host errors on machine checks.

Cc: stable@vger.kernel.org
Fixes: c929500d ("s390/nmi: s390: New low level handling for machine check happening in guest")
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

parent 1ea1d6a8

arch/s390/kernel/nmi.c

+8 −1

Original line number	Diff line number	Diff line
		@@ -264,7 +264,14 @@ static int notrace s390_validate_registers(union mci mci, int umode)
		/* Validate vector registers */
		union ctlreg0 cr0;

		if (!mci.vr) {
		/*
		* The vector validity must only be checked if not running a
		* KVM guest. For KVM guests the machine check is forwarded by
		* KVM and it is the responsibility of the guest to take
		* appropriate actions. The host vector or FPU values have been
		* saved by KVM and will be restored by KVM.
		*/
		if (!mci.vr && !test_cpu_flag(CIF_MCCK_GUEST)) {
		/*
		* Vector registers can't be restored. If the kernel
		* currently uses vector registers the system is