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KVM: arm64: Restore missing ISB on nVHE __tlb_switch_to_guest 

Commit a0e50aa3f4 ("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: a0e50aa3f4 ("KVM: arm64: Factor out stage 2 page table data from struct kvm")
Reported-by: Andrew Scull <ascull@google.com>
Reported-by: Thomas Tai <thomas.tai@oracle.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2020-07-13 15:15:14 +01:00
parent 620cf45f7a
commit 452d622279
1 changed files with 7 additions and 0 deletions
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7
arch/arm64/kvm/hyp/nvhe/tlb.c
View File

@ -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)