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Patch "ARM: KVM: user_mem_abort: support stage 2 MMIO page mapping" has been added to the 3.14-stable tree

PATCH [email protected] 1 participant 1 message Jun 27, 2015

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

ARM: KVM: user_mem_abort: support stage 2 MMIO page mapping

to the 3.14-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-kvm-user_mem_abort-support-stage-2-mmio-page-mapping.patch
and it can be found in the queue-3.14 subdirectory.

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

Quoted 1 line

From b88657674d39fc2127d62d0de9ca142e166443c8 Mon Sep 17 00:00:00 2001

From: Kim Phillips <[email protected]>
Date: Thu, 26 Jun 2014 01:45:51 +0100
Subject: ARM: KVM: user_mem_abort: support stage 2 MMIO page mapping

From: Kim Phillips <[email protected]>

commit b88657674d39fc2127d62d0de9ca142e166443c8 upstream.

A userspace process can map device MMIO memory via VFIO or /dev/mem, e.g., for platform device passthrough support in QEMU.

During early development, we found the PAGE_S2 memory type being used for MMIO mappings. This patch corrects that by using the more strongly ordered memory type for device MMIO mappings: PAGE_S2_DEVICE.

Signed-off-by Kim Phillips <[email protected]>
Acked-by Christoffer Dall <[email protected]>
Acked-by Will Deacon <[email protected]>
Signed-off-by Marc Zyngier <[email protected]>
Signed-off-by Shannon Zhao <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 arch/arm/kvm/mmu.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)
arch/arm/kvm/mmu.c +8 -3
@@ -759,6 +759,7 @@ static int user_mem_abort(struct kvm_vcp
 	struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
 	struct vm_area_struct *vma;
 	pfn_t pfn;
+	pgprot_t mem_type = PAGE_S2;
 
 	write_fault = kvm_is_write_fault(kvm_vcpu_get_hsr(vcpu));
 	if (fault_status == FSC_PERM && !write_fault) {

@@ -809,6 +810,9 @@ static int user_mem_abort(struct kvm_vcp
 	if (is_error_pfn(pfn))
 		return -EFAULT;
 
+	if (kvm_is_mmio_pfn(pfn))
+		mem_type = PAGE_S2_DEVICE;
+
 	spin_lock(&kvm->mmu_lock);
 	if (mmu_notifier_retry(kvm, mmu_seq))
 		goto out_unlock;

@@ -816,7 +820,7 @@ static int user_mem_abort(struct kvm_vcp
 		hugetlb = transparent_hugepage_adjust(&pfn, &fault_ipa);
 
 	if (hugetlb) {
-		pmd_t new_pmd = pfn_pmd(pfn, PAGE_S2);
+		pmd_t new_pmd = pfn_pmd(pfn, mem_type);
 		new_pmd = pmd_mkhuge(new_pmd);
 		if (writable) {
 			kvm_set_s2pmd_writable(&new_pmd);

@@ -825,13 +829,14 @@ static int user_mem_abort(struct kvm_vcp
 		coherent_cache_guest_page(vcpu, hva & PMD_MASK, PMD_SIZE);
 		ret = stage2_set_pmd_huge(kvm, memcache, fault_ipa, &new_pmd);
 	} else {
-		pte_t new_pte = pfn_pte(pfn, PAGE_S2);
+		pte_t new_pte = pfn_pte(pfn, mem_type);
 		if (writable) {
 			kvm_set_s2pte_writable(&new_pte);
 			kvm_set_pfn_dirty(pfn);
 		}
 		coherent_cache_guest_page(vcpu, hva, PAGE_SIZE);
-		ret = stage2_set_pte(kvm, memcache, fault_ipa, &new_pte, false);
+		ret = stage2_set_pte(kvm, memcache, fault_ipa, &new_pte,
+				     mem_type == PAGE_S2_DEVICE);
 	}

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

queue-3.14/arm-kvm-user_mem_abort-support-stage-2-mmio-page-mapping.patch