[PATCH 2/5] KVM: e500: use shadow TLB entry as witness for writability

Paolo Bonzini
2025-01-12T09:55:41Z

kvmppc_e500_ref_setup is returning whether the guest TLB entry is writable,
which is than passed to kvm_release_faultin_page. This makes little sense
for two reasons: first, because the function sets up the private data for
the page and the return value feels like it has been bolted on the side;
second, because what really matters is whether the _shadow_ TLB entry is
writable. If it is not writable, the page can be released as non-dirty.
Shift from using tlbe_is_writable(gtlbe) to doing the same check on
the shadow TLB entry.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/powerpc/kvm/e500_mmu_host.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c
index 6824e8139801..c266c02f120f 100644
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c
@@ -242,7 +242,7 @@ static inline int tlbe_is_writable(struct kvm_book3e_206_tlb_entry *tlbe)
return tlbe->mas7_3 & (MAS3_SW|MAS3_UW);
}

-static inline bool kvmppc_e500_ref_setup(struct tlbe_ref *ref,
+static inline void kvmppc_e500_ref_setup(struct tlbe_ref *ref,
struct kvm_book3e_206_tlb_entry *gtlbe,
kvm_pfn_t pfn, unsigned int wimg)
{
@@ -251,8 +251,6 @@ static inline bool kvmppc_e500_ref_setup(struct tlbe_ref *ref,

/* Use guest supplied MAS2_G and MAS2_E */
ref->flags |= (gtlbe->mas2 & MAS2_ATTRIB_MASK) | wimg;
-
- return tlbe_is_writable(gtlbe);
}

static inline void kvmppc_e500_ref_release(struct tlbe_ref *ref)
@@ -489,9 +487,10 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
}
local_irq_restore(flags);

- writable = kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg);
+ kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg);
kvmppc_e500_setup_stlbe(&vcpu_e500->vcpu, gtlbe, tsize,
ref, gvaddr, stlbe);
+ writable = tlbe_is_writable(stlbe);

/* Clear i-cache for new pages */
kvmppc_mmu_flush_icache(pfn);
--
2.47.1