+ kvm-use-follow_pfnmap-api.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: KVM: use follow_pfnmap API
has been added to the -mm mm-unstable branch.  Its filename is
     kvm-use-follow_pfnmap-api.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kvm-use-follow_pfnmap-api.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Peter Xu <peterx@redhat.com>
Subject: KVM: use follow_pfnmap API
Date: Mon, 26 Aug 2024 16:43:44 -0400

Use the new pfnmap API to allow huge MMIO mappings for VMs.  The rest work
is done perfectly on the other side (host_pfn_mapping_level()).

Link: https://lkml.kernel.org/r/20240826204353.2228736-11-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Gavin Shan <gshan@redhat.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 virt/kvm/kvm_main.c |   19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

--- a/virt/kvm/kvm_main.c~kvm-use-follow_pfnmap-api
+++ a/virt/kvm/kvm_main.c
@@ -2860,13 +2860,11 @@ static int hva_to_pfn_remapped(struct vm
 			       unsigned long addr, bool write_fault,
 			       bool *writable, kvm_pfn_t *p_pfn)
 {
+	struct follow_pfnmap_args args = { .vma = vma, .address = addr };
 	kvm_pfn_t pfn;
-	pte_t *ptep;
-	pte_t pte;
-	spinlock_t *ptl;
 	int r;
 
-	r = follow_pte(vma, addr, &ptep, &ptl);
+	r = follow_pfnmap_start(&args);
 	if (r) {
 		/*
 		 * get_user_pages fails for VM_IO and VM_PFNMAP vmas and does
@@ -2881,21 +2879,19 @@ static int hva_to_pfn_remapped(struct vm
 		if (r)
 			return r;
 
-		r = follow_pte(vma, addr, &ptep, &ptl);
+		r = follow_pfnmap_start(&args);
 		if (r)
 			return r;
 	}
 
-	pte = ptep_get(ptep);
-
-	if (write_fault && !pte_write(pte)) {
+	if (write_fault && !args.writable) {
 		pfn = KVM_PFN_ERR_RO_FAULT;
 		goto out;
 	}
 
 	if (writable)
-		*writable = pte_write(pte);
-	pfn = pte_pfn(pte);
+		*writable = args.writable;
+	pfn = args.pfn;
 
 	/*
 	 * Get a reference here because callers of *hva_to_pfn* and
@@ -2916,9 +2912,8 @@ static int hva_to_pfn_remapped(struct vm
 	 */
 	if (!kvm_try_get_pfn(pfn))
 		r = -EFAULT;
-
 out:
-	pte_unmap_unlock(ptep, ptl);
+	follow_pfnmap_end(&args);
 	*p_pfn = pfn;
 
 	return r;
_

Patches currently in -mm which might be from peterx@redhat.com are

mm-dax-dump-start-address-in-fault-handler.patch
mm-mprotect-push-mmu-notifier-to-puds.patch
mm-powerpc-add-missing-pud-helpers.patch
mm-x86-make-pud_leaf-only-care-about-pse-bit.patch
mm-x86-implement-arch_check_zapped_pud.patch
mm-x86-add-missing-pud-helpers.patch
mm-mprotect-fix-dax-pud-handlings.patch
mm-introduce-arch_supports_huge_pfnmap-and-special-bits-to-pmd-pud.patch
mm-drop-is_huge_zero_pud.patch
mm-mark-special-bits-for-huge-pfn-mappings-when-inject.patch
mm-allow-thp-orders-for-pfnmaps.patch
mm-gup-detect-huge-pfnmap-entries-in-gup-fast.patch
mm-pagewalk-check-pfnmap-for-folio_walk_start.patch
mm-fork-accept-huge-pfnmap-entries.patch
mm-always-define-pxx_pgprot.patch
mm-new-follow_pfnmap-api.patch
kvm-use-follow_pfnmap-api.patch
s390-pci_mmio-use-follow_pfnmap-api.patch
mm-x86-pat-use-the-new-follow_pfnmap-api.patch
vfio-use-the-new-follow_pfnmap-api.patch
acrn-use-the-new-follow_pfnmap-api.patch
mm-access_process_vm-use-the-new-follow_pfnmap-api.patch
mm-remove-follow_pte.patch
mm-x86-support-large-pfn-mappings.patch
mm-arm64-support-large-pfn-mappings.patch