KVM: arm64: Support dirty page tracking for PUD hugepages

In preparation for creating PUD hugepages at stage 2, add support for
write protecting PUD hugepages when they are encountered. Write
protecting guest tables is used to track dirty pages when migrating
VMs.

Also, provide trivial implementations of required kvm_s2pud_* helpers
to allow sharing of code with arm32.

Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
[ Replaced BUG() => WARN_ON() in arm32 pud helpers ]
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index e6eff8bf5d7f94c58e03ae61be66ce46f503dfc8..9fe6c30eb2fccd255e1ceddf3a1d432bb011421e 100644 (file)
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -87,6 +87,21 @@ void kvm_clear_hyp_idmap(void);
 
 #define kvm_pmd_mkhuge(pmd)    pmd_mkhuge(pmd)
 
+/*
+ * The following kvm_*pud*() functions are provided strictly to allow
+ * sharing code with arm64. They should never be called in practice.
+ */
+static inline void kvm_set_s2pud_readonly(pud_t *pud)
+{
+       WARN_ON(1);
+}
+
+static inline bool kvm_s2pud_readonly(pud_t *pud)
+{
+       WARN_ON(1);
+       return false;
+}
+
 static inline pte_t kvm_s2pte_mkwrite(pte_t pte)
 {
        pte_val(pte) |= L_PTE_S2_RDWR;

diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 13d482710292b7d14e851d15a17d3532af9f1376..8da6d1b2a196bd02229a6921f56c63b6239700e3 100644 (file)
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -251,6 +251,16 @@ static inline bool kvm_s2pmd_exec(pmd_t *pmdp)
        return !(READ_ONCE(pmd_val(*pmdp)) & PMD_S2_XN);
 }
 
+static inline void kvm_set_s2pud_readonly(pud_t *pudp)
+{
+       kvm_set_s2pte_readonly((pte_t *)pudp);
+}
+
+static inline bool kvm_s2pud_readonly(pud_t *pudp)
+{
+       return kvm_s2pte_readonly((pte_t *)pudp);
+}
+
 #define hyp_pte_table_empty(ptep) kvm_page_empty(ptep)
 
 #ifdef __PAGETABLE_PMD_FOLDED

diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index fb5325f7a1acf52886636d490e0519c36fd89761..1c669c3c12081f74c35b0cd6c59bd61a4bd12293 100644 (file)
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -1347,9 +1347,12 @@ static void  stage2_wp_puds(struct kvm *kvm, pgd_t *pgd,
        do {
                next = stage2_pud_addr_end(kvm, addr, end);
                if (!stage2_pud_none(kvm, *pud)) {
-                       /* TODO:PUD not supported, revisit later if supported */
-                       BUG_ON(stage2_pud_huge(kvm, *pud));
-                       stage2_wp_pmds(kvm, pud, addr, next);
+                       if (stage2_pud_huge(kvm, *pud)) {
+                               if (!kvm_s2pud_readonly(pud))
+                                       kvm_set_s2pud_readonly(pud);
+                       } else {
+                               stage2_wp_pmds(kvm, pud, addr, next);
+                       }
                }
        } while (pud++, addr = next, addr != end);
 }
@@ -1392,7 +1395,7 @@ static void stage2_wp_range(struct kvm *kvm, phys_addr_t addr, phys_addr_t end)
  *
  * Called to start logging dirty pages after memory region
  * KVM_MEM_LOG_DIRTY_PAGES operation is called. After this function returns
- * all present PMD and PTEs are write protected in the memory region.
+ * all present PUD, PMD and PTEs are write protected in the memory region.
  * Afterwards read of dirty page log can be called.
  *
  * Acquires kvm_mmu_lock. Called with kvm->slots_lock mutex acquired,