diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index 286644c729ba204534501db1f9a2cad9158921e5..552c31f5a3f70a20c0cc755cce61ccf399b4f706 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -44,6 +44,7 @@
#ifndef __ASSEMBLY__
+#include <linux/highmem.h>
#include <asm/cacheflush.h>
#include <asm/pgalloc.h>
@@ -188,6 +189,36 @@ static inline void coherent_cache_guest_page(struct kvm_vcpu *vcpu, hva_t hva,
}
}
+static inline void __kvm_flush_dcache_pte(pte_t pte)
+{
+ void *va = kmap_atomic(pte_page(pte));
+
+ kvm_flush_dcache_to_poc(va, PAGE_SIZE);
+
+ kunmap_atomic(va);
+}
+
+static inline void __kvm_flush_dcache_pmd(pmd_t pmd)
+{
+ unsigned long size = PMD_SIZE;
+ pfn_t pfn = pmd_pfn(pmd);
+
+ while (size) {
+ void *va = kmap_atomic_pfn(pfn);
+
+ kvm_flush_dcache_to_poc(va, PAGE_SIZE);
+
+ pfn++;
+ size -= PAGE_SIZE;
+
+ kunmap_atomic(va);
+ }
+}
+
+static inline void __kvm_flush_dcache_pud(pud_t pud)
+{
+}
+
#define kvm_virt_to_phys(x) virt_to_idmap((unsigned long)(x))
void kvm_set_way_flush(struct kvm_vcpu *vcpu);
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 106737e309b1473aca8e27001bbe02c5b17f32d4..78e68abcb01fcc0825243749417570e74eb5d7fa 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -58,6 +58,26 @@ static void kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa)
kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, kvm, ipa);
}
+/*
+ * D-Cache management functions. They take the page table entries by
+ * value, as they are flushing the cache using the kernel mapping (or
+ * kmap on 32bit).
+ */
+static void kvm_flush_dcache_pte(pte_t pte)
+{
+ __kvm_flush_dcache_pte(pte);
+}
+
+static void kvm_flush_dcache_pmd(pmd_t pmd)
+{
+ __kvm_flush_dcache_pmd(pmd);
+}
+
+static void kvm_flush_dcache_pud(pud_t pud)
+{
+ __kvm_flush_dcache_pud(pud);
+}
+
static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
int min, int max)
{
@@ -119,6 +139,26 @@ static void clear_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr)
put_page(virt_to_page(pmd));
}
+/*
+ * Unmapping vs dcache management:
+ *
+ * If a guest maps certain memory pages as uncached, all writes will
+ * bypass the data cache and go directly to RAM. However, the CPUs
+ * can still speculate reads (not writes) and fill cache lines with
+ * data.
+ *
+ * Those cache lines will be *clean* cache lines though, so a
+ * clean+invalidate operation is equivalent to an invalidate
+ * operation, because no cache lines are marked dirty.
+ *
+ * Those clean cache lines could be filled prior to an uncached write
+ * by the guest, and the cache coherent IO subsystem would therefore
+ * end up writing old data to disk.
+ *
+ * This is why right after unmapping a page/section and invalidating
+ * the corresponding TLBs, we call kvm_flush_dcache_p*() to make sure
+ * the IO subsystem will never hit in the cache.
+ */
static void unmap_ptes(struct kvm *kvm, pmd_t *pmd,
phys_addr_t addr, phys_addr_t end)
{
@@ -128,9 +168,16 @@ static void unmap_ptes(struct kvm *kvm, pmd_t *pmd,
start_pte = pte = pte_offset_kernel(pmd, addr);
do {
if (!pte_none(*pte)) {
+ pte_t old_pte = *pte;
+
kvm_set_pte(pte, __pte(0));
- put_page(virt_to_page(pte));
kvm_tlb_flush_vmid_ipa(kvm, addr);
+
+ /* No need to invalidate the cache for device mappings */
+ if ((pte_val(old_pte) & PAGE_S2_DEVICE) != PAGE_S2_DEVICE)
+ kvm_flush_dcache_pte(old_pte);
+
+ put_page(virt_to_page(pte));
}
} while (pte++, addr += PAGE_SIZE, addr != end);
@@ -149,8 +196,13 @@ static void unmap_pmds(struct kvm *kvm, pud_t *pud,
next = kvm_pmd_addr_end(addr, end);
if (!pmd_none(*pmd)) {
if (kvm_pmd_huge(*pmd)) {
+ pmd_t old_pmd = *pmd;
+
pmd_clear(pmd);
kvm_tlb_flush_vmid_ipa(kvm, addr);
+
+ kvm_flush_dcache_pmd(old_pmd);
+
put_page(virt_to_page(pmd));
} else {
unmap_ptes(kvm, pmd, addr, next);
@@ -173,8 +225,13 @@ static void unmap_puds(struct kvm *kvm, pgd_t *pgd,
next = kvm_pud_addr_end(addr, end);
if (!pud_none(*pud)) {
if (pud_huge(*pud)) {
+ pud_t old_pud = *pud;
+
pud_clear(pud);
kvm_tlb_flush_vmid_ipa(kvm, addr);
+
+ kvm_flush_dcache_pud(old_pud);
+
put_page(virt_to_page(pud));
} else {
unmap_pmds(kvm, pud, addr, next);
@@ -209,10 +266,9 @@ static void stage2_flush_ptes(struct kvm *kvm, pmd_t *pmd,
pte = pte_offset_kernel(pmd, addr);
do {
- if (!pte_none(*pte)) {
- hva_t hva = gfn_to_hva(kvm, addr >> PAGE_SHIFT);
- kvm_flush_dcache_to_poc((void*)hva, PAGE_SIZE);
- }
+ if (!pte_none(*pte) &&
+ (pte_val(*pte) & PAGE_S2_DEVICE) != PAGE_S2_DEVICE)
+ kvm_flush_dcache_pte(*pte);
} while (pte++, addr += PAGE_SIZE, addr != end);
}
@@ -226,12 +282,10 @@ static void stage2_flush_pmds(struct kvm *kvm, pud_t *pud,
do {
next = kvm_pmd_addr_end(addr, end);
if (!pmd_none(*pmd)) {
- if (kvm_pmd_huge(*pmd)) {
- hva_t hva = gfn_to_hva(kvm, addr >> PAGE_SHIFT);
- kvm_flush_dcache_to_poc((void*)hva, PMD_SIZE);
- } else {
+ if (kvm_pmd_huge(*pmd))
+ kvm_flush_dcache_pmd(*pmd);
+ else
stage2_flush_ptes(kvm, pmd, addr, next);
- }
}
} while (pmd++, addr = next, addr != end);
}
@@ -246,12 +300,10 @@ static void stage2_flush_puds(struct kvm *kvm, pgd_t *pgd,
do {
next = kvm_pud_addr_end(addr, end);
if (!pud_none(*pud)) {
- if (pud_huge(*pud)) {
- hva_t hva = gfn_to_hva(kvm, addr >> PAGE_SHIFT);
- kvm_flush_dcache_to_poc((void*)hva, PUD_SIZE);
- } else {
+ if (pud_huge(*pud))
+ kvm_flush_dcache_pud(*pud);
+ else
stage2_flush_pmds(kvm, pud, addr, next);
- }
}
} while (pud++, addr = next, addr != end);
}
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 92d22e94a79b3fabbca845b2f4d7b2b61c4692a8..cbdc236d81f8d76eb8cb036e24af01ea80515b89 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -258,6 +258,24 @@ static inline void coherent_cache_guest_page(struct kvm_vcpu *vcpu, hva_t hva,
}
}
+static inline void __kvm_flush_dcache_pte(pte_t pte)
+{
+ struct page *page = pte_page(pte);
+ kvm_flush_dcache_to_poc(page_address(page), PAGE_SIZE);
+}
+
+static inline void __kvm_flush_dcache_pmd(pmd_t pmd)
+{
+ struct page *page = pmd_page(pmd);
+ kvm_flush_dcache_to_poc(page_address(page), PMD_SIZE);
+}
+
+static inline void __kvm_flush_dcache_pud(pud_t pud)
+{
+ struct page *page = pud_page(pud);
+ kvm_flush_dcache_to_poc(page_address(page), PUD_SIZE);
+}
+
#define kvm_virt_to_phys(x) __virt_to_phys((unsigned long)(x))
void kvm_set_way_flush(struct kvm_vcpu *vcpu);