Patch "ARM/arm64: KVM: correct PTE uncachedness check" has been added to the 4.1-stable tree

This is a note to let you know that I've just added the patch titled

ARM/arm64: KVM: correct PTE uncachedness check

to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
arm-arm64-kvm-correct-pte-uncachedness-check.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ard Biesheuvel <[email protected]>
Date: Thu, 3 Dec 2015 09:25:22 +0100
Subject: ARM/arm64: KVM: correct PTE uncachedness check

From: Ard Biesheuvel <[email protected]>

commit 0de58f852875a0f0dcfb120bb8433e4e73c7803b upstream.

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.

---
 arch/arm/kvm/mmu.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -218,7 +218,7 @@ static void unmap_ptes(struct kvm *kvm,
 			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
 
 	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);
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.1/arm-arm64-kvm-test-properly-for-a-pte-s-uncachedness.patch queue-4.1/arm64-mm-use-correct-mapping-granularity-under-debug_rodata.patch queue-4.1/arm-arm64-kvm-correct-pte-uncachedness-check.patch