* David Hildenbrand <da...@redhat.com> [250512 08:34]:
> ... by factoring it out from track_pfn_remap() into
> pfnmap_setup_cachemode() and provide pfnmap_setup_cachemode_pfn() as
> a replacement for track_pfn_insert().
>
> For PMDs/PUDs, we keep checking a single pfn only. Add some documentation,
> and also document why it is valid to not check the whole pfn range.
>
> We'll reuse pfnmap_setup_cachemode() from core MM next.
>
> Acked-by: Ingo Molnar <mi...@kernel.org> # x86 bits
> Signed-off-by: David Hildenbrand <da...@redhat.com>
Reviewed-by: Liam R. Howlett <liam.howl...@oracle.com>
> ---
> arch/x86/mm/pat/memtype.c | 24 ++++++------------
> include/linux/pgtable.h | 52 +++++++++++++++++++++++++++++++++------
> mm/huge_memory.c | 5 ++--
> mm/memory.c | 4 +--
> 4 files changed, 57 insertions(+), 28 deletions(-)
>
> diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c
> index edec5859651d6..fa78facc6f633 100644
> --- a/arch/x86/mm/pat/memtype.c
> +++ b/arch/x86/mm/pat/memtype.c
> @@ -1031,7 +1031,6 @@ int track_pfn_remap(struct vm_area_struct *vma,
> pgprot_t *prot,
> unsigned long pfn, unsigned long addr, unsigned long size)
> {
> resource_size_t paddr = (resource_size_t)pfn << PAGE_SHIFT;
> - enum page_cache_mode pcm;
>
> /* reserve the whole chunk starting from paddr */
> if (!vma || (addr == vma->vm_start
> @@ -1044,13 +1043,17 @@ int track_pfn_remap(struct vm_area_struct *vma,
> pgprot_t *prot,
> return ret;
> }
>
> + return pfnmap_setup_cachemode(pfn, size, prot);
> +}
> +
> +int pfnmap_setup_cachemode(unsigned long pfn, unsigned long size, pgprot_t
> *prot)
> +{
> + resource_size_t paddr = (resource_size_t)pfn << PAGE_SHIFT;
> + enum page_cache_mode pcm;
> +
> if (!pat_enabled())
> return 0;
>
> - /*
> - * For anything smaller than the vma size we set prot based on the
> - * lookup.
> - */
> pcm = lookup_memtype(paddr);
>
> /* Check memtype for the remaining pages */
> @@ -1065,17 +1068,6 @@ int track_pfn_remap(struct vm_area_struct *vma,
> pgprot_t *prot,
> return 0;
> }
>
> -void track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot, pfn_t pfn)
> -{
> - enum page_cache_mode pcm;
> -
> - if (!pat_enabled())
> - return;
> -
> - pcm = lookup_memtype(pfn_t_to_phys(pfn));
> - pgprot_set_cachemode(prot, pcm);
> -}
> -
> /*
> * untrack_pfn is called while unmapping a pfnmap for a region.
> * untrack can be called for a specific region indicated by pfn and size or
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index f1e890b604609..be1745839871c 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -1496,13 +1496,10 @@ static inline int track_pfn_remap(struct
> vm_area_struct *vma, pgprot_t *prot,
> return 0;
> }
>
> -/*
> - * track_pfn_insert is called when a _new_ single pfn is established
> - * by vmf_insert_pfn().
> - */
> -static inline void track_pfn_insert(struct vm_area_struct *vma, pgprot_t
> *prot,
> - pfn_t pfn)
> +static inline int pfnmap_setup_cachemode(unsigned long pfn, unsigned long
> size,
> + pgprot_t *prot)
> {
> + return 0;
> }
>
> /*
> @@ -1552,8 +1549,32 @@ static inline void untrack_pfn_clear(struct
> vm_area_struct *vma)
> extern int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
> unsigned long pfn, unsigned long addr,
> unsigned long size);
> -extern void track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
> - pfn_t pfn);
> +
> +/**
> + * pfnmap_setup_cachemode - setup the cachemode in the pgprot for a pfn range
> + * @pfn: the start of the pfn range
> + * @size: the size of the pfn range in bytes
> + * @prot: the pgprot to modify
> + *
> + * Lookup the cachemode for the pfn range starting at @pfn with the size
> + * @size and store it in @prot, leaving other data in @prot unchanged.
> + *
> + * This allows for a hardware implementation to have fine-grained control of
> + * memory cache behavior at page level granularity. Without a hardware
> + * implementation, this function does nothing.
> + *
> + * Currently there is only one implementation for this - x86 Page Attribute
> + * Table (PAT). See Documentation/arch/x86/pat.rst for more details.
> + *
> + * This function can fail if the pfn range spans pfns that require differing
> + * cachemodes. If the pfn range was previously verified to have a single
> + * cachemode, it is sufficient to query only a single pfn. The assumption is
> + * that this is the case for drivers using the vmf_insert_pfn*() interface.
> + *
> + * Returns 0 on success and -EINVAL on error.
> + */
> +int pfnmap_setup_cachemode(unsigned long pfn, unsigned long size,
> + pgprot_t *prot);
> extern int track_pfn_copy(struct vm_area_struct *dst_vma,
> struct vm_area_struct *src_vma, unsigned long *pfn);
> extern void untrack_pfn_copy(struct vm_area_struct *dst_vma,
> @@ -1563,6 +1584,21 @@ extern void untrack_pfn(struct vm_area_struct *vma,
> unsigned long pfn,
> extern void untrack_pfn_clear(struct vm_area_struct *vma);
> #endif
>
> +/**
> + * pfnmap_setup_cachemode_pfn - setup the cachemode in the pgprot for a pfn
> + * @pfn: the pfn
> + * @prot: the pgprot to modify
> + *
> + * Lookup the cachemode for @pfn and store it in @prot, leaving other
> + * data in @prot unchanged.
> + *
> + * See pfnmap_setup_cachemode() for details.
> + */
> +static inline void pfnmap_setup_cachemode_pfn(unsigned long pfn, pgprot_t
> *prot)
> +{
> + pfnmap_setup_cachemode(pfn, PAGE_SIZE, prot);
> +}
> +
> #ifdef CONFIG_MMU
> #ifdef __HAVE_COLOR_ZERO_PAGE
> static inline int is_zero_pfn(unsigned long pfn)
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 2780a12b25f01..d3e66136e41a3 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1455,7 +1455,8 @@ vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf,
> pfn_t pfn, bool write)
> return VM_FAULT_OOM;
> }
>
> - track_pfn_insert(vma, &pgprot, pfn);
> + pfnmap_setup_cachemode_pfn(pfn_t_to_pfn(pfn), &pgprot);
> +
> ptl = pmd_lock(vma->vm_mm, vmf->pmd);
> error = insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write,
> pgtable);
> @@ -1577,7 +1578,7 @@ vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf,
> pfn_t pfn, bool write)
> if (addr < vma->vm_start || addr >= vma->vm_end)
> return VM_FAULT_SIGBUS;
>
> - track_pfn_insert(vma, &pgprot, pfn);
> + pfnmap_setup_cachemode_pfn(pfn_t_to_pfn(pfn), &pgprot);
>
> ptl = pud_lock(vma->vm_mm, vmf->pud);
> insert_pfn_pud(vma, addr, vmf->pud, pfn, write);
> diff --git a/mm/memory.c b/mm/memory.c
> index 99af83434e7c5..064fc55d8eab9 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2564,7 +2564,7 @@ vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct
> *vma, unsigned long addr,
> if (!pfn_modify_allowed(pfn, pgprot))
> return VM_FAULT_SIGBUS;
>
> - track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
> + pfnmap_setup_cachemode_pfn(pfn, &pgprot);
>
> return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
> false);
> @@ -2627,7 +2627,7 @@ static vm_fault_t __vm_insert_mixed(struct
> vm_area_struct *vma,
> if (addr < vma->vm_start || addr >= vma->vm_end)
> return VM_FAULT_SIGBUS;
>
> - track_pfn_insert(vma, &pgprot, pfn);
> + pfnmap_setup_cachemode_pfn(pfn_t_to_pfn(pfn), &pgprot);
>
> if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot))
> return VM_FAULT_SIGBUS;
> --
> 2.49.0
>
