From: Huang Ying <[email protected]> Shared Virtual Memory (SVM) allows a kernel memory mapping to be shared between CPU and and a device which requested a supervisor PASID. Both devices and IOMMU units have TLBs that cache entries from CPU's page tables. We need to get a chance to flush them at the same time when we flush the CPU TLBs.
We already have an existing MMU notifiers for userspace updates, however we lack the same thing for kernel page table updates. To implement the MMU notification mechanism for the kernel address space, a kernel MMU notifier chain is defined and will be called whenever the CPU TLB is flushed for the kernel address space. As consumer of this notifier, the IOMMU SVM implementations will register callbacks on this notifier and manage the cache entries in both IOTLB and DevTLB. Cc: Ashok Raj <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Kees Cook <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Kirill A. Shutemov <[email protected]> Cc: Matthew Wilcox <[email protected]> Cc: Dave Jiang <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Vegard Nossum <[email protected]> Cc: [email protected] Cc: [email protected] Tested-by: CQ Tang <[email protected]> Signed-off-by: Huang Ying <[email protected]> Signed-off-by: Lu Baolu <[email protected]> --- arch/x86/mm/tlb.c | 2 ++ include/linux/mmu_notifier.h | 33 +++++++++++++++++++++++++++++++++ mm/mmu_notifier.c | 27 +++++++++++++++++++++++++++ 3 files changed, 62 insertions(+) diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 3118392cd..5ff104f 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -6,6 +6,7 @@ #include <linux/interrupt.h> #include <linux/export.h> #include <linux/cpu.h> +#include <linux/mmu_notifier.h> #include <asm/tlbflush.h> #include <asm/mmu_context.h> @@ -567,6 +568,7 @@ void flush_tlb_kernel_range(unsigned long start, unsigned long end) info.end = end; on_each_cpu(do_kernel_range_flush, &info, 1); } + kernel_mmu_notifier_invalidate_range(start, end); } void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch) diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h index b25dc9d..44d7c06 100644 --- a/include/linux/mmu_notifier.h +++ b/include/linux/mmu_notifier.h @@ -408,6 +408,25 @@ extern void mmu_notifier_call_srcu(struct rcu_head *rcu, void (*func)(struct rcu_head *rcu)); extern void mmu_notifier_synchronize(void); +struct kernel_mmu_address_range { + unsigned long start; + unsigned long end; +}; + +/* + * Before the virtual address range managed by kernel (vmalloc/kmap) + * is reused, That is, remapped to the new physical addresses, the + * kernel MMU notifier will be called with KERNEL_MMU_INVALIDATE_RANGE + * and struct kernel_mmu_address_range as parameters. This is used to + * manage the remote TLB. + */ +#define KERNEL_MMU_INVALIDATE_RANGE 1 +extern int kernel_mmu_notifier_register(struct notifier_block *nb); +extern int kernel_mmu_notifier_unregister(struct notifier_block *nb); + +extern int kernel_mmu_notifier_invalidate_range(unsigned long start, + unsigned long end); + #else /* CONFIG_MMU_NOTIFIER */ static inline int mm_has_notifiers(struct mm_struct *mm) @@ -474,6 +493,20 @@ static inline void mmu_notifier_mm_destroy(struct mm_struct *mm) #define pudp_huge_clear_flush_notify pudp_huge_clear_flush #define set_pte_at_notify set_pte_at +static inline int kernel_mmu_notifier_register(struct notifier_block *nb) +{ + return 0; +} + +static inline int kernel_mmu_notifier_unregister(struct notifier_block *nb) +{ + return 0; +} + +static inline void kernel_mmu_notifier_invalidate_range(unsigned long start, + unsigned long end) +{ +} #endif /* CONFIG_MMU_NOTIFIER */ #endif /* _LINUX_MMU_NOTIFIER_H */ diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c index 96edb33..52f816a 100644 --- a/mm/mmu_notifier.c +++ b/mm/mmu_notifier.c @@ -393,3 +393,30 @@ void mmu_notifier_unregister_no_release(struct mmu_notifier *mn, mmdrop(mm); } EXPORT_SYMBOL_GPL(mmu_notifier_unregister_no_release); + +static ATOMIC_NOTIFIER_HEAD(kernel_mmu_notifier_list); + +int kernel_mmu_notifier_register(struct notifier_block *nb) +{ + return atomic_notifier_chain_register(&kernel_mmu_notifier_list, nb); +} +EXPORT_SYMBOL_GPL(kernel_mmu_notifier_register); + +int kernel_mmu_notifier_unregister(struct notifier_block *nb) +{ + return atomic_notifier_chain_unregister(&kernel_mmu_notifier_list, nb); +} +EXPORT_SYMBOL_GPL(kernel_mmu_notifier_unregister); + +int kernel_mmu_notifier_invalidate_range(unsigned long start, + unsigned long end) +{ + struct kernel_mmu_address_range range = { + .start = start, + .end = end, + }; + + return atomic_notifier_call_chain(&kernel_mmu_notifier_list, + KERNEL_MMU_INVALIDATE_RANGE, + &range); +} -- 2.7.4 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
