[PATCH v12 01/84] KVM: arm64: Release pfn, i.e. put page, if copying MTE tags hits ZONE_DEVICE

Sean Christopherson
2024-07-26T23:52:54Z

Put the page reference acquired by gfn_to_pfn_prot() if
kvm_vm_ioctl_mte_copy_tags() runs into ZONE_DEVICE memory. KVM's less-
than-stellar heuristics for dealing with pfn-mapped memory means that KVM
can get a page reference to ZONE_DEVICE memory.

Fixes: f0376edb1ddc ("KVM: arm64: Add ioctl to fetch/store tags in a guest")
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/arm64/kvm/guest.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 11098eb7eb44..e1f0ff08836a 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -1059,6 +1059,7 @@ int kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm,
page = pfn_to_online_page(pfn);
if (!page) {
/* Reject ZONE_DEVICE memory */
+ kvm_release_pfn_clean(pfn);
ret = -EFAULT;
goto out;
}