Commit 91dc54c3 authored by Marc Zyngier's avatar Marc Zyngier Committed by Greg Kroah-Hartman

arm/arm64: KVM: Enforce unconditional flush to PoC when mapping to stage-2

commit 8f36ebaf upstream.

When we fault in a page, we flush it to the PoC (Point of Coherency)
if the faulting vcpu has its own caches off, so that it can observe
the page we just brought it.

But if the vcpu has its caches on, we skip that step. Bad things
happen when *another* vcpu tries to access that page with its own
caches disabled. At that point, there is no garantee that the
data has made it to the PoC, and we access stale data.

The obvious fix is to always flush to PoC when a page is faulted
in, no matter what the state of the vcpu is.

Fixes: 2d58b733 ("arm64: KVM: force cache clean on page fault when caches are off")
Reviewed-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6039863d
......@@ -150,18 +150,12 @@ static inline void __coherent_cache_guest_page(struct kvm_vcpu *vcpu,
* and iterate over the range.
*/
bool need_flush = !vcpu_has_cache_enabled(vcpu) || ipa_uncached;
VM_BUG_ON(size & ~PAGE_MASK);
if (!need_flush && !icache_is_pipt())
goto vipt_cache;
while (size) {
void *va = kmap_atomic_pfn(pfn);
if (need_flush)
kvm_flush_dcache_to_poc(va, PAGE_SIZE);
kvm_flush_dcache_to_poc(va, PAGE_SIZE);
if (icache_is_pipt())
__cpuc_coherent_user_range((unsigned long)va,
......@@ -173,7 +167,6 @@ static inline void __coherent_cache_guest_page(struct kvm_vcpu *vcpu,
kunmap_atomic(va);
}
vipt_cache:
if (!icache_is_pipt() && !icache_is_vivt_asid_tagged()) {
/* any kind of VIPT cache */
__flush_icache_all();
......
......@@ -241,8 +241,7 @@ static inline void __coherent_cache_guest_page(struct kvm_vcpu *vcpu,
{
void *va = page_address(pfn_to_page(pfn));
if (!vcpu_has_cache_enabled(vcpu) || ipa_uncached)
kvm_flush_dcache_to_poc(va, size);
kvm_flush_dcache_to_poc(va, size);
if (!icache_is_aliasing()) { /* PIPT */
flush_icache_range((unsigned long)va,
......
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