vfio: use the new follow_pfnmap API

JIRA: https://issues.redhat.com/browse/RHEL-73613

commit a77f948
Author: Peter Xu <peterx@redhat.com>
Date:   Mon Aug 26 16:43:47 2024 -0400

    vfio: use the new follow_pfnmap API

    Use the new API that can understand huge pfn mappings.

    Link: https://lkml.kernel.org/r/20240826204353.2228736-14-peterx@redhat.com
    Signed-off-by: Peter Xu <peterx@redhat.com>
    Cc: Alex Williamson <alex.williamson@redhat.com>
    Cc: Jason Gunthorpe <jgg@nvidia.com>
    Cc: Alexander Gordeev <agordeev@linux.ibm.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: Matthew Wilcox <willy@infradead.org>
    Cc: Niklas Schnelle <schnelle@linux.ibm.com>
    Cc: Paolo Bonzini <pbonzini@redhat.com>
    Cc: Ryan Roberts <ryan.roberts@arm.com>
    Cc: Sean Christopherson <seanjc@google.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>

Signed-off-by: Donald Dutile <ddutile@redhat.com>

Author: ddutile

drivers/vfio/vfio_iommu_type1.c

@@ -515,12 +515,10 @@ static int follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm,
 			    unsigned long vaddr, unsigned long *pfn,
 			    bool write_fault)
 {
-	pte_t *ptep;
-	pte_t pte;
-	spinlock_t *ptl;
+	struct follow_pfnmap_args args = { .vma = vma, .address = vaddr };
 	int ret;
 
-	ret = follow_pte(vma, vaddr, &ptep, &ptl);
+	ret = follow_pfnmap_start(&args);
 	if (ret) {
 		bool unlocked = false;
 
@@ -534,19 +532,17 @@ static int follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm,
 		if (ret)
 			return ret;
 
-		ret = follow_pte(vma, vaddr, &ptep, &ptl);
+		ret = follow_pfnmap_start(&args);
 		if (ret)
 			return ret;
 	}
 
-	pte = ptep_get(ptep);
-
-	if (write_fault && !pte_write(pte))
+	if (write_fault && !args.writable)
 		ret = -EFAULT;
 	else
-		*pfn = pte_pfn(pte);
+		*pfn = args.pfn;
 
-	pte_unmap_unlock(ptep, ptl);
+	follow_pfnmap_end(&args);
 	return ret;
 }