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authorYanan Wang <wangyanan55@huawei.com>2020-12-02 04:10:34 +0800
committerMarc Zyngier <maz@kernel.org>2020-12-02 09:53:29 +0000
commit7d894834a305568a0168c55d4729216f5f8cb4e6 (patch)
treeb08b0bdcf2f27ff3e775be9dbfb827645d81e416
parent3a0b870e3448302ca2ba703bea1b79b61c3f33c6 (diff)
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KVM: arm64: Add usage of stage 2 fault lookup level in user_mem_abort()
If we get a FSC_PERM fault, just using (logging_active && writable) to determine calling kvm_pgtable_stage2_map(). There will be two more cases we should consider. (1) After logging_active is configged back to false from true. When we get a FSC_PERM fault with write_fault and adjustment of hugepage is needed, we should merge tables back to a block entry. This case is ignored by still calling kvm_pgtable_stage2_relax_perms(), which will lead to an endless loop and guest panic due to soft lockup. (2) We use (FSC_PERM && logging_active && writable) to determine collapsing a block entry into a table by calling kvm_pgtable_stage2_map(). But sometimes we may only need to relax permissions when trying to write to a page other than a block. In this condition,using kvm_pgtable_stage2_relax_perms() will be fine. The ISS filed bit[1:0] in ESR_EL2 regesiter indicates the stage2 lookup level at which a D-abort or I-abort occurred. By comparing granule of the fault lookup level with vma_pagesize, we can strictly distinguish conditions of calling kvm_pgtable_stage2_relax_perms() or kvm_pgtable_stage2_map(), and the above two cases will be well considered. Suggested-by: Keqian Zhu <zhukeqian1@huawei.com> Signed-off-by: Yanan Wang <wangyanan55@huawei.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Acked-by: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20201201201034.116760-4-wangyanan55@huawei.com
-rw-r--r--arch/arm64/include/asm/esr.h1
-rw-r--r--arch/arm64/include/asm/kvm_emulate.h5
-rw-r--r--arch/arm64/kvm/mmu.c11
3 files changed, 15 insertions, 2 deletions
diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h
index 22c81f1edda2..85a3e49f92f4 100644
--- a/arch/arm64/include/asm/esr.h
+++ b/arch/arm64/include/asm/esr.h
@@ -104,6 +104,7 @@
/* Shared ISS fault status code(IFSC/DFSC) for Data/Instruction aborts */
#define ESR_ELx_FSC (0x3F)
#define ESR_ELx_FSC_TYPE (0x3C)
+#define ESR_ELx_FSC_LEVEL (0x03)
#define ESR_ELx_FSC_EXTABT (0x10)
#define ESR_ELx_FSC_SERROR (0x11)
#define ESR_ELx_FSC_ACCESS (0x08)
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 5ef2669ccd6c..00bc6f1234ba 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -350,6 +350,11 @@ static __always_inline u8 kvm_vcpu_trap_get_fault_type(const struct kvm_vcpu *vc
return kvm_vcpu_get_esr(vcpu) & ESR_ELx_FSC_TYPE;
}
+static __always_inline u8 kvm_vcpu_trap_get_fault_level(const struct kvm_vcpu *vcpu)
+{
+ return kvm_vcpu_get_esr(vcpu) & ESR_ELx_FSC_LEVEL;
+}
+
static __always_inline bool kvm_vcpu_abt_issea(const struct kvm_vcpu *vcpu)
{
switch (kvm_vcpu_trap_get_fault(vcpu)) {
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 1a01da9fdc99..75814a02d189 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -754,10 +754,12 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
gfn_t gfn;
kvm_pfn_t pfn;
bool logging_active = memslot_is_logging(memslot);
- unsigned long vma_pagesize;
+ unsigned long fault_level = kvm_vcpu_trap_get_fault_level(vcpu);
+ unsigned long vma_pagesize, fault_granule;
enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R;
struct kvm_pgtable *pgt;
+ fault_granule = 1UL << ARM64_HW_PGTABLE_LEVEL_SHIFT(fault_level);
write_fault = kvm_is_write_fault(vcpu);
exec_fault = kvm_vcpu_trap_is_exec_fault(vcpu);
VM_BUG_ON(write_fault && exec_fault);
@@ -896,7 +898,12 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
else if (cpus_have_const_cap(ARM64_HAS_CACHE_DIC))
prot |= KVM_PGTABLE_PROT_X;
- if (fault_status == FSC_PERM && !(logging_active && writable)) {
+ /*
+ * Under the premise of getting a FSC_PERM fault, we just need to relax
+ * permissions only if vma_pagesize equals fault_granule. Otherwise,
+ * kvm_pgtable_stage2_map() should be called to change block size.
+ */
+ if (fault_status == FSC_PERM && vma_pagesize == fault_granule) {
ret = kvm_pgtable_stage2_relax_perms(pgt, fault_ipa, prot);
} else {
ret = kvm_pgtable_stage2_map(pgt, fault_ipa, vma_pagesize,