| Message ID | 20210607110816.25762-3-steven.price@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | MTE support for KVM guest | expand |
On Mon, Jun 07, 2021 at 12:08:10PM +0100, Steven Price wrote: > From: Catalin Marinas <catalin.marinas@arm.com> > > Currently, on an anonymous page fault, the kernel allocates a zeroed > page and maps it in user space. If the mapping is tagged (PROT_MTE), > set_pte_at() additionally clears the tags under a spinlock to avoid a > race on the page->flags. In order to optimise the lock, clear the page > tags on allocation in __alloc_zeroed_user_highpage() if the vma flags > have VM_MTE set. > > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> > Signed-off-by: Steven Price <steven.price@arm.com> I think you can drop this patch now that Peter's series has been queued via the arm64 tree: https://lore.kernel.org/r/20210602235230.3928842-4-pcc@google.com
On 07/06/2021 18:07, Catalin Marinas wrote: > On Mon, Jun 07, 2021 at 12:08:10PM +0100, Steven Price wrote: >> From: Catalin Marinas <catalin.marinas@arm.com> >> >> Currently, on an anonymous page fault, the kernel allocates a zeroed >> page and maps it in user space. If the mapping is tagged (PROT_MTE), >> set_pte_at() additionally clears the tags under a spinlock to avoid a >> race on the page->flags. In order to optimise the lock, clear the page >> tags on allocation in __alloc_zeroed_user_highpage() if the vma flags >> have VM_MTE set. >> >> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> >> Signed-off-by: Steven Price <steven.price@arm.com> > > I think you can drop this patch now that Peter's series has been queued > via the arm64 tree: > > https://lore.kernel.org/r/20210602235230.3928842-4-pcc@google.com > Thanks for the heads up - I hadn't seen that land. I'll drop this patch from the next posting. Steve
diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h index 012cffc574e8..97853570d0f1 100644 --- a/arch/arm64/include/asm/page.h +++ b/arch/arm64/include/asm/page.h @@ -13,6 +13,7 @@ #ifndef __ASSEMBLY__ #include <linux/personality.h> /* for READ_IMPLIES_EXEC */ +#include <linux/types.h> #include <asm/pgtable-types.h> struct page; @@ -28,8 +29,9 @@ void copy_user_highpage(struct page *to, struct page *from, void copy_highpage(struct page *to, struct page *from); #define __HAVE_ARCH_COPY_HIGHPAGE -#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr) \ - alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr) +struct page *__alloc_zeroed_user_highpage(gfp_t movableflags, + struct vm_area_struct *vma, + unsigned long vaddr); #define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE #define clear_user_page(page, vaddr, pg) clear_page(page) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 871c82ab0a30..5a03428e97f3 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -921,3 +921,24 @@ void do_debug_exception(unsigned long addr_if_watchpoint, unsigned int esr, debug_exception_exit(regs); } NOKPROBE_SYMBOL(do_debug_exception); + +/* + * Used during anonymous page fault handling. + */ +struct page *__alloc_zeroed_user_highpage(gfp_t movableflags, + struct vm_area_struct *vma, + unsigned long vaddr) +{ + struct page *page; + bool tagged = system_supports_mte() && (vma->vm_flags & VM_MTE); + + page = alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, + vaddr); + if (tagged && page) { + mte_clear_page_tags(page_address(page)); + page_kasan_tag_reset(page); + set_bit(PG_mte_tagged, &page->flags); + } + + return page; +}