Let's assume a guest has created an uncached mapping, and written
to that page. Let's also assume that the host uses a cache-coherent
IO subsystem. Let's finally assume that the host is under memory
pressure and starts to swap things out.
Before this "uncached" page is evicted, we need to make sure it
gets invalidated, or the IO subsystem is going to swap out the
cached view, loosing the data that has been written there.
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
arch/arm/include/asm/kvm_mmu.h | 31 +++++++++++++++++++++++++++
arch/arm/kvm/mmu.c | 46 +++++++++++++++++++++++++++-------------
arch/arm64/include/asm/kvm_mmu.h | 18 ++++++++++++++++
3 files changed, 80 insertions(+), 15 deletions(-)
diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index 63e0ecc..7ceb836 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>
@@ -190,6 +191,36 @@ static inline void coherent_cache_guest_page(struct kvm_vcpu *vcpu, hva_t hva,
#define kvm_virt_to_phys(x) virt_to_idmap((unsigned long)(x))
+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)
+{
+}
+
void stage2_flush_vm(struct kvm *kvm);
#endif /* !__ASSEMBLY__ */
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 1dc9778..1f5b793 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -58,6 +58,21 @@ static void kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa)
kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, kvm, ipa);
}
+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)
{
@@ -128,9 +143,12 @@ 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);
+ 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 +167,10 @@ 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 +193,10 @@ 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 +231,8 @@ 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))
+ kvm_flush_dcache_pte(*pte);
} while (pte++, addr += PAGE_SIZE, addr != end);
}
@@ -226,12 +246,10 @@ 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 +264,10 @@ 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 14a74f1..b7419f5 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -260,6 +260,24 @@ static inline void coherent_cache_guest_page(struct kvm_vcpu *vcpu, hva_t hva,
#define kvm_virt_to_phys(x) __virt_to_phys((unsigned long)(x))
+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);
+}
+
void stage2_flush_vm(struct kvm *kvm);
#endif /* __ASSEMBLY__ */
--
2.1.4
--
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