arm/arm64: KVM: Invalidate data cache on unmap

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
we invalidate potential speculated, clean cache lines that are
sitting there, or the IO subsystem is going to swap out the
cached view, loosing the data that has been written directly
into memory.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 92d22e94a79b..cbdc236d81f8 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);