diff mbox series

[v1,05/10] powerpc/book3s: Prepare kvmppc_book3s_instantiate_page() for PG_reserved changes

Message ID 20191024120938.11237-6-david@redhat.com (mailing list archive)
State New, archived
Headers show
Series mm: Don't mark hotplugged pages PG_reserved (including ZONE_DEVICE) | expand

Commit Message

David Hildenbrand Oct. 24, 2019, 12:09 p.m. UTC 
Right now, ZONE_DEVICE memory is always set PG_reserved. We want to
change that.

KVM has this weird use case that you can map anything from /dev/mem
into the guest. pfn_valid() is not a reliable check whether the memmap
was initialized and can be touched. pfn_to_online_page() makes sure
that we have an initialized memmap (and don't have ZONE_DEVICE memory).

Rewrite kvmppc_book3s_instantiate_page() similar to kvm_is_reserved_pfn()
to make sure the function produces the same result once we stop setting
ZONE_DEVICE pages PG_reserved.

Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 arch/powerpc/kvm/book3s_64_mmu_radix.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
index 2d415c36a61d..05397c0561fc 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
@@ -801,12 +801,14 @@  int kvmppc_book3s_instantiate_page(struct kvm_vcpu *vcpu,
 					   writing, upgrade_p);
 		if (is_error_noslot_pfn(pfn))
 			return -EFAULT;
-		page = NULL;
-		if (pfn_valid(pfn)) {
-			page = pfn_to_page(pfn);
-			if (PageReserved(page))
-				page = NULL;
-		}
+		/*
+		 * We treat any pages that are not online (not managed by the
+		 * buddy) as reserved - this includes ZONE_DEVICE pages and
+		 * pages without a memmap (e.g., mapped via /dev/mem).
+		 */
+		page = pfn_to_online_page(pfn);
+		if (page && PageReserved(page))
+			page = NULL;
 	}
 
 	/*