linux-kernel - [PATCH v12 59/84] KVM: PPC: Use __kvm_faultin_pfn() to handle page faults on Book3s HV

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Message-ID: <20240726235234.228822-60-seanjc@google.com>
Date: Fri, 26 Jul 2024 16:52:08 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>, Marc Zyngier <maz@...nel.org>, 
	Oliver Upton <oliver.upton@...ux.dev>, Tianrui Zhao <zhaotianrui@...ngson.cn>, 
	Bibo Mao <maobibo@...ngson.cn>, Huacai Chen <chenhuacai@...nel.org>, 
	Michael Ellerman <mpe@...erman.id.au>, Anup Patel <anup@...infault.org>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>, Christian Borntraeger <borntraeger@...ux.ibm.com>, 
	Janosch Frank <frankja@...ux.ibm.com>, Claudio Imbrenda <imbrenda@...ux.ibm.com>, 
	Sean Christopherson <seanjc@...gle.com>
Cc: kvm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, loongarch@...ts.linux.dev, linux-mips@...r.kernel.org, 
	linuxppc-dev@...ts.ozlabs.org, kvm-riscv@...ts.infradead.org, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	David Matlack <dmatlack@...gle.com>, David Stevens <stevensd@...omium.org>
Subject: [PATCH v12 59/84] KVM: PPC: Use __kvm_faultin_pfn() to handle page
 faults on Book3s HV

Replace Book3s HV's homebrewed 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@...gle.com>
---
 arch/powerpc/kvm/book3s_64_mmu_hv.c | 25 ++++---------------------
 1 file changed, 4 insertions(+), 21 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 2f1d58984b41..f305395cf26e 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -603,27 +603,10 @@ int kvmppc_book3s_hv_page_fault(struct kvm_vcpu *vcpu,
 	write_ok = writing;
 	hva = gfn_to_hva_memslot(memslot, gfn);
 
-	/*
-	 * 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.
-	 */
-	if (get_user_page_fast_only(hva, FOLL_WRITE, &page)) {
-		write_ok = true;
-	} else {
-		/* Call KVM generic code to do the slow-path check */
-		pfn = __gfn_to_pfn_memslot(memslot, gfn, false, NULL,
-					   writing, &write_ok);
-		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,
+				&write_ok, &page);
+	if (is_error_noslot_pfn(pfn))
+		return -EFAULT;
 
 	/*
 	 * Read the PTE from the process' radix tree and use that
-- 
2.46.0.rc1.232.g9752f9e123-goog