KVM: arm/arm64: Skip updating PTE entry if no change
authorPunit Agrawal <punit.agrawal@arm.com>
Mon, 13 Aug 2018 10:43:51 +0000 (11:43 +0100)
committerMarc Zyngier <marc.zyngier@arm.com>
Mon, 13 Aug 2018 14:32:01 +0000 (15:32 +0100)
commit976d34e2dab10ece5ea8fe7090b7692913f89084
tree116675a97ba2812fccb4aec6119786eb2b452b1d
parent86658b819cd0a9aa584cd84453ed268a6f013770
KVM: arm/arm64: Skip updating PTE entry if no change

When there is contention on faulting in a particular page table entry
at stage 2, the break-before-make requirement of the architecture can
lead to additional refaulting due to TLB invalidation.

Avoid this by skipping a page table update if the new value of the PTE
matches the previous value.

Cc: stable@vger.kernel.org
Fixes: d5d8184d35c9 ("KVM: ARM: Memory virtualization setup")
Reviewed-by: Suzuki Poulose <suzuki.poulose@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
virt/kvm/arm/mmu.c