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KVM: PPC: Use __kvm_faultin_pfn() to handle page faults on Book3s Radix

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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>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-62-seanjc@google.com>
This commit is contained in:
Sean Christopherson 2024-10-10 11:24:03 -07:00 committed by Paolo Bonzini
parent 0865ba14b4
commit 431d2f7dcb
1 changed files with 5 additions and 24 deletions
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29
arch/powerpc/kvm/book3s_64_mmu_radix.c
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@ -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