Re: [PATCH] kvm: arm: Enforce PTE mappings at stage2 when needed
Hi Suzuki,
On 2019/3/12 17:52, Suzuki K Poulose wrote:
commit 6794ad5443a2118 ("KVM: arm/arm64: Fix unintended stage 2 PMD mappings")
made the checks to skip huge mappings, stricter. However it introduced
a bug where we still use huge mappings, ignoring the flag to
use PTE mappings, by not reseting the vma_pagesize to PAGE_SIZE.
Also, the checks do not cover the PUD huge pages, that was
under review during the same period. This patch fixes both
the issues.
Fixes : 6794ad5443a2118 ("KVM: arm/arm64: Fix unintended stage 2 PMD mappings")
Reported-by: Zenghui Yu
Cc: Zenghui Yu
Cc: Christoffer Dall
Cc: Marc Zyngier
Signed-off-by: Suzuki K Poulose
---
Thanks for Cc-ing me. It works fine now!
zenghui
virt/kvm/arm/mmu.c | 43 +--
1 file changed, 21 insertions(+), 22 deletions(-)
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 30251e2..66e0fbb5 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -1595,8 +1595,9 @@ static void kvm_send_hwpoison_signal(unsigned long
address,
send_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, lsb, current);
}
-static bool fault_supports_stage2_pmd_mappings(struct kvm_memory_slot *memslot,
- unsigned long hva)
+static bool fault_supports_stage2_huge_mapping(struct kvm_memory_slot *memslot,
+ unsigned long hva,
+ unsigned long map_size)
{
gpa_t gpa_start, gpa_end;
hva_t uaddr_start, uaddr_end;
@@ -1612,34 +1613,34 @@ static bool fault_supports_stage2_pmd_mappings(struct
kvm_memory_slot *memslot,
/*
* Pages belonging to memslots that don't have the same alignment
-* within a PMD for userspace and IPA cannot be mapped with stage-2
-* PMD entries, because we'll end up mapping the wrong pages.
+* within a PMD/PUD for userspace and IPA cannot be mapped with stage-2
+* PMD/PUD entries, because we'll end up mapping the wrong pages.
*
* Consider a layout like the following:
*
*memslot->userspace_addr:
*+-+++---+
-*|abcde|fgh Stage-1 PMD|Stage-1 PMD tv|xyz|
+*|abcde|fgh Stage-1 block |Stage-1 block tv|xyz|
*+-+++---+
*
*memslot->base_gfn << PAGE_SIZE:
* +---+++-+
-* |abc|def Stage-2 PMD|Stage-2 PMD |tvxyz|
+* |abc|def Stage-2 block |Stage-2 block |tvxyz|
* +---+++-+
*
-* If we create those stage-2 PMDs, we'll end up with this incorrect
+* If we create those stage-2 blocks, we'll end up with this incorrect
* mapping:
* d -> f
* e -> g
* f -> h
*/
- if ((gpa_start & ~S2_PMD_MASK) != (uaddr_start & ~S2_PMD_MASK))
+ if ((gpa_start & (map_size - 1)) != (uaddr_start & (map_size - 1)))
return false;
/*
* Next, let's make sure we're not trying to map anything not covered
-* by the memslot. This means we have to prohibit PMD size mappings
-* for the beginning and end of a non-PMD aligned and non-PMD sized
+* by the memslot. This means we have to prohibit block size mappings
+* for the beginning and end of a non-block aligned and non-block sized
* memory slot (illustrated by the head and tail parts of the
* userspace view above containing pages 'abcde' and 'xyz',
* respectively).
@@ -1648,8 +1649,8 @@ static bool fault_supports_stage2_pmd_mappings(struct
kvm_memory_slot *memslot,
* userspace_addr or the base_gfn, as both are equally aligned (per
* the check above) and equally sized.
*/
- return (hva & S2_PMD_MASK) >= uaddr_start &&
- (hva & S2_PMD_MASK) + S2_PMD_SIZE <= uaddr_end;
+ return (hva & ~(map_size - 1)) >= uaddr_start &&
+ (hva & ~(map_size - 1)) + map_size <= uaddr_end;
}
static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
@@ -1678,12 +1679,6 @@ static int user_mem_abort(struct kvm_vcpu *vcpu,
phys_addr_t fault_ipa,
return -EFAULT;
}
- if (!fault_supports_stage2_pmd_mappings(memslot, hva))
- force_pte = true;
-
- if (logging_active)
- force_pte = true;
-
/* Let's check if we will get back a huge page backed by hugetlbfs */
down_read(>mm->mmap_sem);
vma = find_vma_intersection(current->mm, hva, hva + 1);
@@ -1694,6 +1689,12 @@ static int user_mem_abort(struct kvm_vcpu *vcpu,
phys_addr_t fault_ipa,
}
vma_pagesize = vma_kernel_pagesize(vma);
+ if
[PATCH] kvm: arm: Enforce PTE mappings at stage2 when needed
commit 6794ad5443a2118 ("KVM: arm/arm64: Fix unintended stage 2 PMD mappings")
made the checks to skip huge mappings, stricter. However it introduced
a bug where we still use huge mappings, ignoring the flag to
use PTE mappings, by not reseting the vma_pagesize to PAGE_SIZE.
Also, the checks do not cover the PUD huge pages, that was
under review during the same period. This patch fixes both
the issues.
Fixes : 6794ad5443a2118 ("KVM: arm/arm64: Fix unintended stage 2 PMD mappings")
Reported-by: Zenghui Yu
Cc: Zenghui Yu
Cc: Christoffer Dall
Cc: Marc Zyngier
Signed-off-by: Suzuki K Poulose
---
virt/kvm/arm/mmu.c | 43 +--
1 file changed, 21 insertions(+), 22 deletions(-)
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 30251e2..66e0fbb5 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -1595,8 +1595,9 @@ static void kvm_send_hwpoison_signal(unsigned long
address,
send_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, lsb, current);
}
-static bool fault_supports_stage2_pmd_mappings(struct kvm_memory_slot *memslot,
- unsigned long hva)
+static bool fault_supports_stage2_huge_mapping(struct kvm_memory_slot *memslot,
+ unsigned long hva,
+ unsigned long map_size)
{
gpa_t gpa_start, gpa_end;
hva_t uaddr_start, uaddr_end;
@@ -1612,34 +1613,34 @@ static bool fault_supports_stage2_pmd_mappings(struct
kvm_memory_slot *memslot,
/*
* Pages belonging to memslots that don't have the same alignment
-* within a PMD for userspace and IPA cannot be mapped with stage-2
-* PMD entries, because we'll end up mapping the wrong pages.
+* within a PMD/PUD for userspace and IPA cannot be mapped with stage-2
+* PMD/PUD entries, because we'll end up mapping the wrong pages.
*
* Consider a layout like the following:
*
*memslot->userspace_addr:
*+-+++---+
-*|abcde|fgh Stage-1 PMD|Stage-1 PMD tv|xyz|
+*|abcde|fgh Stage-1 block |Stage-1 block tv|xyz|
*+-+++---+
*
*memslot->base_gfn << PAGE_SIZE:
* +---+++-+
-* |abc|def Stage-2 PMD|Stage-2 PMD |tvxyz|
+* |abc|def Stage-2 block |Stage-2 block |tvxyz|
* +---+++-+
*
-* If we create those stage-2 PMDs, we'll end up with this incorrect
+* If we create those stage-2 blocks, we'll end up with this incorrect
* mapping:
* d -> f
* e -> g
* f -> h
*/
- if ((gpa_start & ~S2_PMD_MASK) != (uaddr_start & ~S2_PMD_MASK))
+ if ((gpa_start & (map_size - 1)) != (uaddr_start & (map_size - 1)))
return false;
/*
* Next, let's make sure we're not trying to map anything not covered
-* by the memslot. This means we have to prohibit PMD size mappings
-* for the beginning and end of a non-PMD aligned and non-PMD sized
+* by the memslot. This means we have to prohibit block size mappings
+* for the beginning and end of a non-block aligned and non-block sized
* memory slot (illustrated by the head and tail parts of the
* userspace view above containing pages 'abcde' and 'xyz',
* respectively).
@@ -1648,8 +1649,8 @@ static bool fault_supports_stage2_pmd_mappings(struct
kvm_memory_slot *memslot,
* userspace_addr or the base_gfn, as both are equally aligned (per
* the check above) and equally sized.
*/
- return (hva & S2_PMD_MASK) >= uaddr_start &&
- (hva & S2_PMD_MASK) + S2_PMD_SIZE <= uaddr_end;
+ return (hva & ~(map_size - 1)) >= uaddr_start &&
+ (hva & ~(map_size - 1)) + map_size <= uaddr_end;
}
static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
@@ -1678,12 +1679,6 @@ static int user_mem_abort(struct kvm_vcpu *vcpu,
phys_addr_t fault_ipa,
return -EFAULT;
}
- if (!fault_supports_stage2_pmd_mappings(memslot, hva))
- force_pte = true;
-
- if (logging_active)
- force_pte = true;
-
/* Let's check if we will get back a huge page backed by hugetlbfs */
down_read(>mm->mmap_sem);
vma = find_vma_intersection(current->mm, hva, hva + 1);
@@ -1694,6 +1689,12 @@ static int user_mem_abort(struct kvm_vcpu *vcpu,
phys_addr_t fault_ipa,
}
vma_pagesize = vma_kernel_pagesize(vma);
+ if (logging_active ||
+ !fault_supports_stage2_huge_mapping(memslot, hva, vma_pagesize)) {
+
