[PATCH 16/20] [Bionic] (upstream) KVM: PPC: Book3S HV: radix: Refine IO region partition scope attributes

[Leonardo Bras]

From: Nicholas Piggin <npiggin at gmail.com>

BugLink: https://bugs.launchpad.net/bugs/1788098

When the radix fault handler has no page from the process address
space (e.g., for IO memory), it looks up the process pte and sets
partition table pte using that to get attributes like CI and guarded.
If the process table entry is to be writable, set _PAGE_DIRTY as well
to avoid an RC update. If not, then ensure _PAGE_DIRTY does not come
across. Set _PAGE_ACCESSED as well to avoid RC update.

Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
Signed-off-by: Paul Mackerras <paulus at ozlabs.org>
(cherry picked from commit bc64dd0e1c4eddbec75dd5aa86b60c2a834aaef3 v4.19)
Signed-off-by: Leonardo Bras <leonardo at linux.ibm.com>
---
 arch/powerpc/kvm/book3s_64_mmu_radix.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
index e55db915af49..b0ba3628adc2 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
@@ -674,9 +674,13 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 			unsigned long mask = (1ul << shift) - PAGE_SIZE;
 			pte = __pte(pte_val(pte) | (hva & mask));
 		}
-		if (!(writing || upgrade_write))
-			pte = __pte(pte_val(pte) & ~ _PAGE_WRITE);
-		pte = __pte(pte_val(pte) | _PAGE_EXEC);
+		pte = __pte(pte_val(pte) | _PAGE_EXEC | _PAGE_ACCESSED);
+		if (writing || upgrade_write) {
+			if (pte_val(pte) & _PAGE_WRITE)
+				pte = __pte(pte_val(pte) | _PAGE_DIRTY);
+		} else {
+			pte = __pte(pte_val(pte) & ~(_PAGE_WRITE | _PAGE_DIRTY));
+		}
 	}
 
 	/* Allocate space in the tree and write the PTE */
-- 
2.20.1