From 452d62227958e149e5c7b0084a559c0957c3ff2a Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Mon, 13 Jul 2020 15:15:14 +0100 Subject: KVM: arm64: Restore missing ISB on nVHE __tlb_switch_to_guest Commit a0e50aa3f4a8 ("KVM: arm64: Factor out stage 2 page table data from struct kvm") dropped the ISB after __load_guest_stage2(), only leaving the one that is required when the speculative AT workaround is in effect. As Andrew points it: "This alternative is 'backwards' to avoid a double ISB as there is one in __load_guest_stage2 when the workaround is active." Restore the missing ISB, conditionned on the AT workaround not being active. Fixes: a0e50aa3f4a8 ("KVM: arm64: Factor out stage 2 page table data from struct kvm") Reported-by: Andrew Scull Reported-by: Thomas Tai Signed-off-by: Marc Zyngier --- arch/arm64/kvm/hyp/nvhe/tlb.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'arch') diff --git a/arch/arm64/kvm/hyp/nvhe/tlb.c b/arch/arm64/kvm/hyp/nvhe/tlb.c index 69eae608d670..b15d65a42042 100644 --- a/arch/arm64/kvm/hyp/nvhe/tlb.c +++ b/arch/arm64/kvm/hyp/nvhe/tlb.c @@ -31,7 +31,14 @@ static void __tlb_switch_to_guest(struct kvm_s2_mmu *mmu, isb(); } + /* + * __load_guest_stage2() includes an ISB only when the AT + * workaround is applied. Take care of the opposite condition, + * ensuring that we always have an ISB, but not two ISBs back + * to back. + */ __load_guest_stage2(mmu); + asm(ALTERNATIVE("isb", "nop", ARM64_WORKAROUND_SPECULATIVE_AT)); } static void __tlb_switch_to_host(struct tlb_inv_context *cxt) -- cgit v1.2.3