[RFC PATCH v3 2/2] arm64: tlb: Use the TLBI RANGE feature in arm64

Zhenyu Ye
2020-04-14T11:28:35Z

Add __TLBI_VADDR_RANGE macro and __flush_tlb_range_directly()
interface.

Signed-off-by: Zhenyu Ye <yezhenyu2@huawei.com>
---
arch/arm64/include/asm/tlb.h | 7 +-
arch/arm64/include/asm/tlbflush.h | 114 +++++++++++++++++++++++++++++-
2 files changed, 119 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h
index b76df828e6b7..3a1816770bd1 100644
--- a/arch/arm64/include/asm/tlb.h
+++ b/arch/arm64/include/asm/tlb.h
@@ -38,7 +38,12 @@ static inline void tlb_flush(struct mmu_gather *tlb)
return;
}

- __flush_tlb_range(&vma, tlb->start, tlb->end, stride, last_level);
+ if (cpus_have_const_cap(ARM64_HAS_TLBI_RANGE))
+ __flush_tlb_range_directly(&vma, tlb->start, tlb->end,
+ stride, last_level);
+ else
+ __flush_tlb_range(&vma, tlb->start, tlb->end,
+ stride, last_level);
}

static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
index bc3949064725..a482188ea563 100644
--- a/arch/arm64/include/asm/tlbflush.h
+++ b/arch/arm64/include/asm/tlbflush.h
@@ -59,6 +59,44 @@
__ta; \
})

+/*
+ * This macro creates a properly formatted VA operand for the TLBI RANGE.
+ * The value bit assignments are:
+ *
+ * +----------+------+-------+-------+-------+----------------------+
+ * | ASID | TG | SCALE | NUM | TTL | BADDR |
+ * +-----------------+-------+-------+-------+----------------------+
+ * |63 48|47 46|45 44|43 39|38 37|36 0|
+ *
+ * The address range is determined by below formula:
+ * [BADDR, BADDR + (NUM + 1) * 2^(5*SCALE + 1) * PAGESIZE)
+ *
+ */
+#define __TLBI_VADDR_RANGE(addr, asid, tg, scale, num, ttl) \
+ ({ \
+ unsigned long __ta = (addr) >> PAGE_SHIFT; \
+ __ta &= GENMASK_ULL(36, 0); \
+ __ta |= (unsigned long)(ttl) << 37; \
+ __ta |= (unsigned long)(num) << 39; \
+ __ta |= (unsigned long)(scale) << 44; \
+ __ta |= (unsigned long)(tg) << 46; \
+ __ta |= (unsigned long)(asid) << 48; \
+ __ta; \
+ })
+
+#define TLB_RANGE_MASK_SHIFT 5
+#define TLB_RANGE_MASK GENMASK_ULL(TLB_RANGE_MASK_SHIFT - 1, 0)
+
+/*
+ * __TG defines translation granule of the system, which is defined by
+ * PAGE_SHIFT. Used by TTL.
+ * - 4KB : 1
+ * - 16KB : 2
+ * - 64KB : 3
+ */
+#define __TG ((PAGE_SHIFT - 12) / 2 + 1)
+
+
/*
* TLB Invalidation
* ================
@@ -171,12 +209,83 @@ static inline void flush_tlb_page(struct vm_area_struct *vma,
dsb(ish);
}

+/* The maximum range size of one TLBI-RANGE instruction */
+#define MAX_TLBI_RANGE_SIZE (1UL << 21)
+
+/*
+ * This interface uses the *rvale1is* instruction to flush TLBs
+ * in [start, end) directly.
+ * This instruction is supported from ARM v8.4.
+ */
+static inline void __flush_tlb_range_directly(struct vm_area_struct *vma,
+ unsigned long start, unsigned long end,
+ unsigned long stride, bool last_level)
+{
+ int num = 0;
+ int scale = 0;
+ unsigned long asid = ASID(vma->vm_mm);
+ unsigned long addr = 0;
+ unsigned long range_size;
+
+ start = round_down(start, stride);
+ end = round_up(end, stride);
+ range_size = (end - start) >> PAGE_SHIFT;
+
+ if (range_size > MAX_TLBI_RANGE_SIZE) {
+ flush_tlb_mm(vma->vm_mm);
+ return;
+ }
+
+ dsb(ishst);
+
+ /*
+ * The minimum size of TLB RANGE is 2 PAGE;
+ * Use normal TLB instruction to handle odd PAGEs
+ */
+ if (range_size % 2 == 1) {
+ addr = __TLBI_VADDR(start, asid);
+ if (last_level) {
+ __tlbi(vale1is, addr);
+ __tlbi_user(vale1is, addr);
+ } else {
+ __tlbi(vae1is, addr);
+ __tlbi_user(vae1is, addr);
+ }
+ start += 1 << PAGE_SHIFT;
+ range_size -= 1;
+ }
+
+ range_size >>= 1;
+ while (range_size > 0) {
+ num = (range_size & TLB_RANGE_MASK) - 1;
+ if (num >= 0) {
+ addr = __TLBI_VADDR_RANGE(start, asid, __TG,
+ scale, num, 0);
+ if (last_level) {
+ __tlbi(rvale1is, addr);
+ __tlbi_user(rvale1is, addr);
+ } else {
+ __tlbi(rvae1is, addr);
+ __tlbi_user(rvae1is, addr);
+ }
+ start += (num + 1) << (5 * scale + 1) << PAGE_SHIFT;
+ }
+ scale++;
+ range_size >>= TLB_RANGE_MASK_SHIFT;
+ }
+ dsb(ish);
+}
+
/*
* This is meant to avoid soft lock-ups on large TLB flushing ranges and not
* necessarily a performance improvement.
*/
#define MAX_TLBI_OPS PTRS_PER_PTE

+/*
+ * This interface uses the *vae1is* instruction to flush TLBs
+ * in [start, end) one by one.
+ */
static inline void __flush_tlb_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end,
unsigned long stride, bool last_level)
@@ -218,7 +327,10 @@ static inline void flush_tlb_range(struct vm_area_struct *vma,
* We cannot use leaf-only invalidation here, since we may be invalidating
* table entries as part of collapsing hugepages or moving page tables.
*/
- __flush_tlb_range(vma, start, end, PAGE_SIZE, false);
+ if (cpus_have_const_cap(ARM64_HAS_TLBI_RANGE))
+ __flush_tlb_range_directly(vma, start, end, PAGE_SIZE, false);
+ else
+ __flush_tlb_range(vma, start, end, PAGE_SIZE, false);
}

static inline void flush_tlb_kernel_range(unsigned long start, unsigned long end)
--
2.19.1