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    SubjectRe: [PATCH v3 02/34] mm: Add generic flush_icache_pages() and documentation
    On Tue, Feb 28, 2023 at 09:37:05PM +0000, Matthew Wilcox (Oracle) wrote:
    > flush_icache_page() is deprecated but not yet removed, so add
    > a range version of it. Change the documentation to refer to
    > update_mmu_cache_range() instead of update_mmu_cache().
    >
    > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

    Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>

    > ---
    > Documentation/core-api/cachetlb.rst | 35 +++++++++++++++--------------
    > include/asm-generic/cacheflush.h | 5 +++++
    > 2 files changed, 23 insertions(+), 17 deletions(-)
    >
    > diff --git a/Documentation/core-api/cachetlb.rst b/Documentation/core-api/cachetlb.rst
    > index 5c0552e78c58..d4c9e2a28d36 100644
    > --- a/Documentation/core-api/cachetlb.rst
    > +++ b/Documentation/core-api/cachetlb.rst
    > @@ -88,13 +88,13 @@ changes occur:
    >
    > This is used primarily during fault processing.
    >
    > -5) ``void update_mmu_cache(struct vm_area_struct *vma,
    > - unsigned long address, pte_t *ptep)``
    > +5) ``void update_mmu_cache_range(struct vm_area_struct *vma,
    > + unsigned long address, pte_t *ptep, unsigned int nr)``
    >
    > - At the end of every page fault, this routine is invoked to
    > - tell the architecture specific code that a translation
    > - now exists at virtual address "address" for address space
    > - "vma->vm_mm", in the software page tables.
    > + At the end of every page fault, this routine is invoked to tell
    > + the architecture specific code that translations now exists
    > + in the software page tables for address space "vma->vm_mm"
    > + at virtual address "address" for "nr" consecutive pages.
    >
    > A port may use this information in any way it so chooses.
    > For example, it could use this event to pre-load TLB
    > @@ -306,17 +306,18 @@ maps this page at its virtual address.
    > private". The kernel guarantees that, for pagecache pages, it will
    > clear this bit when such a page first enters the pagecache.
    >
    > - This allows these interfaces to be implemented much more efficiently.
    > - It allows one to "defer" (perhaps indefinitely) the actual flush if
    > - there are currently no user processes mapping this page. See sparc64's
    > - flush_dcache_page and update_mmu_cache implementations for an example
    > - of how to go about doing this.
    > + This allows these interfaces to be implemented much more
    > + efficiently. It allows one to "defer" (perhaps indefinitely) the
    > + actual flush if there are currently no user processes mapping this
    > + page. See sparc64's flush_dcache_page and update_mmu_cache_range
    > + implementations for an example of how to go about doing this.
    >
    > - The idea is, first at flush_dcache_page() time, if page_file_mapping()
    > - returns a mapping, and mapping_mapped on that mapping returns %false,
    > - just mark the architecture private page flag bit. Later, in
    > - update_mmu_cache(), a check is made of this flag bit, and if set the
    > - flush is done and the flag bit is cleared.
    > + The idea is, first at flush_dcache_page() time, if
    > + page_file_mapping() returns a mapping, and mapping_mapped on that
    > + mapping returns %false, just mark the architecture private page
    > + flag bit. Later, in update_mmu_cache_range(), a check is made
    > + of this flag bit, and if set the flush is done and the flag bit
    > + is cleared.
    >
    > .. important::
    >
    > @@ -369,7 +370,7 @@ maps this page at its virtual address.
    > ``void flush_icache_page(struct vm_area_struct *vma, struct page *page)``
    >
    > All the functionality of flush_icache_page can be implemented in
    > - flush_dcache_page and update_mmu_cache. In the future, the hope
    > + flush_dcache_page and update_mmu_cache_range. In the future, the hope
    > is to remove this interface completely.
    >
    > The final category of APIs is for I/O to deliberately aliased address
    > diff --git a/include/asm-generic/cacheflush.h b/include/asm-generic/cacheflush.h
    > index f46258d1a080..09d51a680765 100644
    > --- a/include/asm-generic/cacheflush.h
    > +++ b/include/asm-generic/cacheflush.h
    > @@ -78,6 +78,11 @@ static inline void flush_icache_range(unsigned long start, unsigned long end)
    > #endif
    >
    > #ifndef flush_icache_page
    > +static inline void flush_icache_pages(struct vm_area_struct *vma,
    > + struct page *page, unsigned int nr)
    > +{
    > +}
    > +
    > static inline void flush_icache_page(struct vm_area_struct *vma,
    > struct page *page)
    > {
    > --
    > 2.39.1
    >
    >

    --
    Sincerely yours,
    Mike.

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