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[5/5] ARM/arm64: KVM: correct PTE uncachedness check

Message ID 1449249440-28878-6-git-send-email-marc.zyngier@arm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Marc Zyngier Dec. 4, 2015, 5:17 p.m. UTC 
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Commit e6fab5442345 ("ARM/arm64: KVM: test properly for a PTE's
uncachedness") modified the logic to test whether a HYP or stage-2
mapping needs flushing, from [incorrectly] interpreting the page table
attributes to [incorrectly] checking whether the PFN that backs the
mapping is covered by host system RAM. The PFN number is part of the
output of the translation, not the input, so we have to use pte_pfn()
on the contents of the PTE, not __phys_to_pfn() on the HYP virtual
address or stage-2 intermediate physical address.

Fixes: e6fab5442345 ("ARM/arm64: KVM: test properly for a PTE's uncachedness")
Cc: stable@vger.kernel.org
Tested-by: Pavel Fedin <p.fedin@samsung.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm/kvm/mmu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
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Patch

diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 7dace90..61d96a6 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -218,7 +218,7 @@  static void unmap_ptes(struct kvm *kvm, pmd_t *pmd,
 			kvm_tlb_flush_vmid_ipa(kvm, addr);
 
 			/* No need to invalidate the cache for device mappings */
-			if (!kvm_is_device_pfn(__phys_to_pfn(addr)))
+			if (!kvm_is_device_pfn(pte_pfn(old_pte)))
 				kvm_flush_dcache_pte(old_pte);
 
 			put_page(virt_to_page(pte));
@@ -310,7 +310,7 @@  static void stage2_flush_ptes(struct kvm *kvm, pmd_t *pmd,
 
 	pte = pte_offset_kernel(pmd, addr);
 	do {
-		if (!pte_none(*pte) && !kvm_is_device_pfn(__phys_to_pfn(addr)))
+		if (!pte_none(*pte) && !kvm_is_device_pfn(pte_pfn(*pte)))
 			kvm_flush_dcache_pte(*pte);
 	} while (pte++, addr += PAGE_SIZE, addr != end);
 }