[PATCH v12 60/84] KVM: PPC: Use __kvm_faultin_pfn() to handle page faults on Book3s Radix

Sean Christopherson
2024-07-27T00:24:40Z

Replace Book3s Radix's homebrewed (read: copy+pasted) fault-in logic with
__kvm_faultin_pfn(), which functionally does pretty much the exact same
thing.

Note, when the code was written, KVM indeed didn't do fast GUP without
"!atomic && !async", but that has long since changed (KVM tries fast GUP
for all writable mappings).

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/powerpc/kvm/book3s_64_mmu_radix.c | 29 +++++---------------------
1 file changed, 5 insertions(+), 24 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
index 8304b6f8fe45..14891d0a3b73 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
@@ -829,40 +829,21 @@ int kvmppc_book3s_instantiate_page(struct kvm_vcpu *vcpu,
unsigned long mmu_seq;
unsigned long hva, gfn = gpa >> PAGE_SHIFT;
bool upgrade_write = false;
- bool *upgrade_p = &upgrade_write;
pte_t pte, *ptep;
unsigned int shift, level;
int ret;
bool large_enable;
+ kvm_pfn_t pfn;

/* used to check for invalidations in progress */
mmu_seq = kvm->mmu_invalidate_seq;
smp_rmb();

- /*
- * Do a fast check first, since __gfn_to_pfn_memslot doesn't
- * do it with !atomic && !async, which is how we call it.
- * We always ask for write permission since the common case
- * is that the page is writable.
- */
hva = gfn_to_hva_memslot(memslot, gfn);
- if (!kvm_ro && get_user_page_fast_only(hva, FOLL_WRITE, &page)) {
- upgrade_write = true;
- } else {
- unsigned long pfn;
-
- /* Call KVM generic code to do the slow-path check */
- pfn = __gfn_to_pfn_memslot(memslot, gfn, false, NULL,
- 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;
- }
- }
+ pfn = __kvm_faultin_pfn(memslot, gfn, writing ? FOLL_WRITE : 0,
+ &upgrade_write, &page);
+ if (is_error_noslot_pfn(pfn))
+ return -EFAULT;

/*
* Read the PTE from the process' radix tree and use that