[PATCH 06/10] KVM: Don't WARN if kvm_pfn_to_page() encounters a "reserved" pfn

From: Sean Christopherson
Date: Thu Apr 28 2022 - 21:04:44 EST


Drop a WARN_ON() if kvm_pfn_to_page() encounters a "reserved" pfn, which
in this context means a struct page that has PG_reserved but is not a/the
ZERO_PAGE and is not a ZONE_DEVICE page. The usage, via gfn_to_page(),
in x86 is safe as gfn_to_page() is used only to retrieve a page from
KVM-controlled memslot, but the usage in PPC and s390 operates on
arbitrary gfns and thus memslots that can be backed by incompatible
memory.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
virt/kvm/kvm_main.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index ab7549195c68..a987188a426f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2703,10 +2703,8 @@ static struct page *kvm_pfn_to_page(kvm_pfn_t pfn)
if (is_error_noslot_pfn(pfn))
return KVM_ERR_PTR_BAD_PAGE;

- if (kvm_is_reserved_pfn(pfn)) {
- WARN_ON(1);
+ if (kvm_is_reserved_pfn(pfn))
return KVM_ERR_PTR_BAD_PAGE;
- }

return pfn_to_page(pfn);
}
--
2.36.0.464.gb9c8b46e94-goog