From 7a3796d2ef5bb948f709467eef1bf96edbfc67a0 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Mon, 23 Oct 2017 17:11:21 +0100 Subject: KVM: arm/arm64: Preserve Exec permission across R/W permission faults So far, we loose the Exec property whenever we take permission faults, as we always reconstruct the PTE/PMD from scratch. This can be counter productive as we can end-up with the following fault sequence: X -> RO -> ROX -> RW -> RWX Instead, we can lookup the existing PTE/PMD and clear the XN bit in the new entry if it was already cleared in the old one, leadig to a much nicer fault sequence: X -> ROX -> RWX Reviewed-by: Christoffer Dall Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall --- arch/arm64/include/asm/kvm_mmu.h | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'arch/arm64') diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h index 1e1b20c..126abef 100644 --- a/arch/arm64/include/asm/kvm_mmu.h +++ b/arch/arm64/include/asm/kvm_mmu.h @@ -203,6 +203,11 @@ static inline bool kvm_s2pte_readonly(pte_t *pte) return (pte_val(*pte) & PTE_S2_RDWR) == PTE_S2_RDONLY; } +static inline bool kvm_s2pte_exec(pte_t *pte) +{ + return !(pte_val(*pte) & PTE_S2_XN); +} + static inline void kvm_set_s2pmd_readonly(pmd_t *pmd) { kvm_set_s2pte_readonly((pte_t *)pmd); @@ -213,6 +218,11 @@ static inline bool kvm_s2pmd_readonly(pmd_t *pmd) return kvm_s2pte_readonly((pte_t *)pmd); } +static inline bool kvm_s2pmd_exec(pmd_t *pmd) +{ + return !(pmd_val(*pmd) & PMD_S2_XN); +} + static inline bool kvm_page_empty(void *ptr) { struct page *ptr_page = virt_to_page(ptr); -- cgit v1.1