On Tue, 27 Jul 2021 19:10:45 +0100,
Will Deacon [off-list ref] wrote:

On Thu, Jul 15, 2021 at 05:31:45PM +0100, Marc Zyngier wrote:

quoted

Make sure we don't issue CMOs when mapping something that
is not a memory address in the S2 page tables.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/hyp/pgtable.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 05321f4165e3..a5874ebd0354 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c

@@ -619,12 +619,16 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
 	}
 
 	/* Perform CMOs before installation of the guest stage-2 PTE */
-	if (mm_ops->dcache_clean_inval_poc && stage2_pte_cacheable(pgt, new))
-		mm_ops->dcache_clean_inval_poc(kvm_pte_follow(new, mm_ops),
-						granule);
-
-	if (mm_ops->icache_inval_pou && stage2_pte_executable(new))
-		mm_ops->icache_inval_pou(kvm_pte_follow(new, mm_ops), granule);
+	if (kvm_phys_is_valid(phys)) {
+		if (mm_ops->dcache_clean_inval_poc &&
+		    stage2_pte_cacheable(pgt, new))
+			mm_ops->dcache_clean_inval_poc(kvm_pte_follow(new,
+								      mm_ops),
+						       granule);
+		if (mm_ops->icache_inval_pou && stage2_pte_executable(new))
+			mm_ops->icache_inval_pou(kvm_pte_follow(new, mm_ops),
+						 granule);
+	}

Given that this check corresponds to checking the validity of 'new', I
wonder whether we'd be better off pushing the validity checks down into
stage2_pte_{cacheable,executable}()?

I.e. have stage2_pte_cacheable() return false if !kvm_pte_valid()

That would work just as well. I'll update the patch.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel