diff mbox series

[v4,09/12] riscv: mm: Use a fixed layout for the MM context ID

Message ID 20240102220134.3229156-10-samuel.holland@sifive.com
State New
Headers
Series riscv: ASID-related and UP-related TLB flush enhancements |

Commit Message

Samuel Holland Jan. 2, 2024, 10 p.m. UTC 
  Currently, the size of the ASID field in the MM context ID dynamically
depends on the number of hardware-supported ASID bits. This requires
reading a global variable to extract either field from the context ID.
Instead, allocate the maximum possible number of bits to the ASID field,
so the layout of the context ID is known at compile-time.

Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
---

(no changes since v1)

 arch/riscv/include/asm/mmu.h      | 4 ++--
 arch/riscv/include/asm/tlbflush.h | 2 --
 arch/riscv/mm/context.c           | 6 ++----
 3 files changed, 4 insertions(+), 8 deletions(-)

Comments

Alexandre Ghiti Jan. 4, 2024, 12:42 p.m. UTC | #1 
On Tue, Jan 2, 2024 at 11:01 PM Samuel Holland
<samuel.holland@sifive.com> wrote:
>
> Currently, the size of the ASID field in the MM context ID dynamically
> depends on the number of hardware-supported ASID bits. This requires
> reading a global variable to extract either field from the context ID.
> Instead, allocate the maximum possible number of bits to the ASID field,
> so the layout of the context ID is known at compile-time.
>
> Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
> ---
>
> (no changes since v1)
>
>  arch/riscv/include/asm/mmu.h      | 4 ++--
>  arch/riscv/include/asm/tlbflush.h | 2 --
>  arch/riscv/mm/context.c           | 6 ++----
>  3 files changed, 4 insertions(+), 8 deletions(-)
>
> diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h
> index a550fbf770be..dc0273f7905f 100644
> --- a/arch/riscv/include/asm/mmu.h
> +++ b/arch/riscv/include/asm/mmu.h
> @@ -26,8 +26,8 @@ typedef struct {
>  #endif
>  } mm_context_t;
>
> -#define cntx2asid(cntx)                ((cntx) & asid_mask)
> -#define cntx2version(cntx)     ((cntx) & ~asid_mask)
> +#define cntx2asid(cntx)                ((cntx) & SATP_ASID_MASK)
> +#define cntx2version(cntx)     ((cntx) & ~SATP_ASID_MASK)
>
>  void __init create_pgd_mapping(pgd_t *pgdp, uintptr_t va, phys_addr_t pa,
>                                phys_addr_t sz, pgprot_t prot);
> diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
> index d9913590f82e..5bfd37cfd8c3 100644
> --- a/arch/riscv/include/asm/tlbflush.h
> +++ b/arch/riscv/include/asm/tlbflush.h
> @@ -15,8 +15,6 @@
>  #define FLUSH_TLB_NO_ASID       ((unsigned long)-1)
>
>  #ifdef CONFIG_MMU
> -extern unsigned long asid_mask;
> -
>  static inline void local_flush_tlb_all(void)
>  {
>         __asm__ __volatile__ ("sfence.vma" : : : "memory");
> diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c
> index 43d005f63253..b5170ac1b742 100644
> --- a/arch/riscv/mm/context.c
> +++ b/arch/riscv/mm/context.c
> @@ -22,7 +22,6 @@ DEFINE_STATIC_KEY_FALSE(use_asid_allocator);
>
>  static unsigned long asid_bits;
>  static unsigned long num_asids;
> -unsigned long asid_mask;
>
>  static atomic_long_t current_version;
>
> @@ -128,7 +127,7 @@ static unsigned long __new_context(struct mm_struct *mm)
>                 goto set_asid;
>
>         /* We're out of ASIDs, so increment current_version */
> -       ver = atomic_long_add_return_relaxed(num_asids, &current_version);
> +       ver = atomic_long_add_return_relaxed(BIT(SATP_ASID_BITS), &current_version);
>
>         /* Flush everything  */
>         __flush_context();
> @@ -247,7 +246,6 @@ static int __init asids_init(void)
>         /* Pre-compute ASID details */
>         if (asid_bits) {
>                 num_asids = 1 << asid_bits;
> -               asid_mask = num_asids - 1;
>         }
>
>         /*
> @@ -255,7 +253,7 @@ static int __init asids_init(void)
>          * at-least twice more than CPUs
>          */
>         if (num_asids > (2 * num_possible_cpus())) {
> -               atomic_long_set(&current_version, num_asids);
> +               atomic_long_set(&current_version, BIT(SATP_ASID_BITS));
>
>                 context_asid_map = bitmap_zalloc(num_asids, GFP_KERNEL);
>                 if (!context_asid_map)
> --
> 2.42.0
>

You can add:

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Thanks,

Alex
diff mbox series

Patch

diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h
index a550fbf770be..dc0273f7905f 100644
--- a/arch/riscv/include/asm/mmu.h
+++ b/arch/riscv/include/asm/mmu.h
@@ -26,8 +26,8 @@  typedef struct {
 #endif
 } mm_context_t;
 
-#define cntx2asid(cntx)		((cntx) & asid_mask)
-#define cntx2version(cntx)	((cntx) & ~asid_mask)
+#define cntx2asid(cntx)		((cntx) & SATP_ASID_MASK)
+#define cntx2version(cntx)	((cntx) & ~SATP_ASID_MASK)
 
 void __init create_pgd_mapping(pgd_t *pgdp, uintptr_t va, phys_addr_t pa,
 			       phys_addr_t sz, pgprot_t prot);
diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
index d9913590f82e..5bfd37cfd8c3 100644
--- a/arch/riscv/include/asm/tlbflush.h
+++ b/arch/riscv/include/asm/tlbflush.h
@@ -15,8 +15,6 @@ 
 #define FLUSH_TLB_NO_ASID       ((unsigned long)-1)
 
 #ifdef CONFIG_MMU
-extern unsigned long asid_mask;
-
 static inline void local_flush_tlb_all(void)
 {
 	__asm__ __volatile__ ("sfence.vma" : : : "memory");
diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c
index 43d005f63253..b5170ac1b742 100644
--- a/arch/riscv/mm/context.c
+++ b/arch/riscv/mm/context.c
@@ -22,7 +22,6 @@  DEFINE_STATIC_KEY_FALSE(use_asid_allocator);
 
 static unsigned long asid_bits;
 static unsigned long num_asids;
-unsigned long asid_mask;
 
 static atomic_long_t current_version;
 
@@ -128,7 +127,7 @@  static unsigned long __new_context(struct mm_struct *mm)
 		goto set_asid;
 
 	/* We're out of ASIDs, so increment current_version */
-	ver = atomic_long_add_return_relaxed(num_asids, &current_version);
+	ver = atomic_long_add_return_relaxed(BIT(SATP_ASID_BITS), &current_version);
 
 	/* Flush everything  */
 	__flush_context();
@@ -247,7 +246,6 @@  static int __init asids_init(void)
 	/* Pre-compute ASID details */
 	if (asid_bits) {
 		num_asids = 1 << asid_bits;
-		asid_mask = num_asids - 1;
 	}
 
 	/*
@@ -255,7 +253,7 @@  static int __init asids_init(void)
 	 * at-least twice more than CPUs
 	 */
 	if (num_asids > (2 * num_possible_cpus())) {
-		atomic_long_set(&current_version, num_asids);
+		atomic_long_set(&current_version, BIT(SATP_ASID_BITS));
 
 		context_asid_map = bitmap_zalloc(num_asids, GFP_KERNEL);
 		if (!context_asid_map)