[PATCH v1 2/3] mm: pass VMA instead of MM to follow_pte()

David Hildenbrand
2024-04-10T15:56:07Z

... and centralize the VM_IO/VM_PFNMAP sanity check in there. We'll
now also perform these sanity checks for direct follow_pte()
invocations.

For generic_access_phys(), we might now check multiple times: nothing to
worry about, really.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
arch/s390/pci/pci_mmio.c | 4 ++--
arch/x86/mm/pat/memtype.c | 5 +----
drivers/vfio/vfio_iommu_type1.c | 4 ++--
drivers/virt/acrn/mm.c | 3 +--
include/linux/mm.h | 2 +-
mm/memory.c | 15 ++++++++-------
virt/kvm/kvm_main.c | 4 ++--
7 files changed, 17 insertions(+), 20 deletions(-)

diff --git a/arch/s390/pci/pci_mmio.c b/arch/s390/pci/pci_mmio.c
index a90499c087f0..5398729bfe1b 100644
--- a/arch/s390/pci/pci_mmio.c
+++ b/arch/s390/pci/pci_mmio.c
@@ -169,7 +169,7 @@ SYSCALL_DEFINE3(s390_pci_mmio_write, unsigned long, mmio_addr,
if (!(vma->vm_flags & VM_WRITE))
goto out_unlock_mmap;

- ret = follow_pte(vma->vm_mm, mmio_addr, &ptep, &ptl);
+ ret = follow_pte(vma, mmio_addr, &ptep, &ptl);
if (ret)
goto out_unlock_mmap;

@@ -308,7 +308,7 @@ SYSCALL_DEFINE3(s390_pci_mmio_read, unsigned long, mmio_addr,
if (!(vma->vm_flags & VM_WRITE))
goto out_unlock_mmap;

- ret = follow_pte(vma->vm_mm, mmio_addr, &ptep, &ptl);
+ ret = follow_pte(vma, mmio_addr, &ptep, &ptl);
if (ret)
goto out_unlock_mmap;

diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c
index d01c3b0bd6eb..bdc2a240c2aa 100644
--- a/arch/x86/mm/pat/memtype.c
+++ b/arch/x86/mm/pat/memtype.c
@@ -954,10 +954,7 @@ static int follow_phys(struct vm_area_struct *vma, unsigned long *prot,
pte_t *ptep, pte;
spinlock_t *ptl;

- if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
- return -EINVAL;
-
- if (follow_pte(vma->vm_mm, vma->vm_start, &ptep, &ptl))
+ if (follow_pte(vma, vma->vm_start, &ptep, &ptl))
return -EINVAL;

pte = ptep_get(ptep);
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index b5c15fe8f9fc..3a0218171cfa 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -518,7 +518,7 @@ static int follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm,
spinlock_t *ptl;
int ret;

- ret = follow_pte(vma->vm_mm, vaddr, &ptep, &ptl);
+ ret = follow_pte(vma, vaddr, &ptep, &ptl);
if (ret) {
bool unlocked = false;

@@ -532,7 +532,7 @@ static int follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm,
if (ret)
return ret;

- ret = follow_pte(vma->vm_mm, vaddr, &ptep, &ptl);
+ ret = follow_pte(vma, vaddr, &ptep, &ptl);
if (ret)
return ret;
}
diff --git a/drivers/virt/acrn/mm.c b/drivers/virt/acrn/mm.c
index 2d98e1e185c4..db8ff1d0ac23 100644
--- a/drivers/virt/acrn/mm.c
+++ b/drivers/virt/acrn/mm.c
@@ -187,8 +187,7 @@ int acrn_vm_ram_map(struct acrn_vm *vm, struct acrn_vm_memmap *memmap)
}

for (i = 0; i < nr_pages; i++) {
- ret = follow_pte(vma->vm_mm,
- memmap->vma_base + i * PAGE_SIZE,
+ ret = follow_pte(vma, memmap->vma_base + i * PAGE_SIZE,
&ptep, &ptl);
if (ret)
break;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ef34cf54c14f..374b307abfc1 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2420,7 +2420,7 @@ void free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
unsigned long end, unsigned long floor, unsigned long ceiling);
int
copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma);
-int follow_pte(struct mm_struct *mm, unsigned long address,
+int follow_pte(struct vm_area_struct *vma, unsigned long address,
pte_t **ptepp, spinlock_t **ptlp);
int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
void *buf, int len, int write);
diff --git a/mm/memory.c b/mm/memory.c
index 78422d1c7381..ab01fb69dc72 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5928,7 +5928,7 @@ int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)

/**
* follow_pte - look up PTE at a user virtual address
- * @mm: the mm_struct of the target address space
+ * @vma: the memory mapping
* @address: user virtual address
* @ptepp: location to store found PTE
* @ptlp: location to store the lock for the PTE
@@ -5947,15 +5947,19 @@ int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
*
* Return: zero on success, -ve otherwise.
*/
-int follow_pte(struct mm_struct *mm, unsigned long address,
+int follow_pte(struct vm_area_struct *vma, unsigned long address,
pte_t **ptepp, spinlock_t **ptlp)
{
+ struct mm_struct *mm = vma->vm_mm;
pgd_t *pgd;
p4d_t *p4d;
pud_t *pud;
pmd_t *pmd;
pte_t *ptep;

+ if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
+ goto out;
+
pgd = pgd_offset(mm, address);
if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
goto out;
@@ -6009,11 +6013,8 @@ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
int offset = offset_in_page(addr);
int ret = -EINVAL;

- if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
- return -EINVAL;
-
retry:
- if (follow_pte(vma->vm_mm, addr, &ptep, &ptl))
+ if (follow_pte(vma, addr, &ptep, &ptl))
return -EINVAL;
pte = ptep_get(ptep);
pte_unmap_unlock(ptep, ptl);
@@ -6028,7 +6029,7 @@ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
if (!maddr)
return -ENOMEM;

- if (follow_pte(vma->vm_mm, addr, &ptep, &ptl))
+ if (follow_pte(vma, addr, &ptep, &ptl))
goto out_unmap;

if (!pte_same(pte, ptep_get(ptep))) {
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index fb49c2a60200..f57dbacb8689 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2902,7 +2902,7 @@ static int hva_to_pfn_remapped(struct vm_area_struct *vma,
spinlock_t *ptl;
int r;

- r = follow_pte(vma->vm_mm, addr, &ptep, &ptl);
+ r = follow_pte(vma, addr, &ptep, &ptl);
if (r) {
/*
* get_user_pages fails for VM_IO and VM_PFNMAP vmas and does
@@ -2917,7 +2917,7 @@ static int hva_to_pfn_remapped(struct vm_area_struct *vma,
if (r)
return r;

- r = follow_pte(vma->vm_mm, addr, &ptep, &ptl);
+ r = follow_pte(vma, addr, &ptep, &ptl);
if (r)
return r;
}
--
2.44.0