Re: [PATCH 1/2] Revert "riscv: mm: notify remote harts about mmu cache updates"

Thx Reviewed-by: Guo Ren guoren@kernel.org

On Sun, Feb 26, 2023 at 11:02 PM Sergey Matyukevich geomatsi@gmail.com wrote:

From: Sergey Matyukevich sergey.matyukevich@syntacore.com

This reverts the remaining bits of commit 4bd1d80efb5a ("riscv: mm: notify remote harts harts about mmu cache updates").

According to bug reports, suggested approach to fix stale TLB entries is not sufficient. It needs to be replaced by a more robust solution.

Fixes: 4bd1d80efb5a ("riscv: mm: notify remote harts about mmu cache updates") Reported-by: Zong Li zong.li@sifive.com Reported-by: Lad Prabhakar prabhakar.mahadev-lad.rj@bp.renesas.com Signed-off-by: Sergey Matyukevich sergey.matyukevich@syntacore.com Cc: stable@vger.kernel.org

---

arch/riscv/include/asm/mmu.h | 2 -- arch/riscv/include/asm/tlbflush.h | 18 ------------------ arch/riscv/mm/context.c | 10 ---------- arch/riscv/mm/tlbflush.c | 28 +++++++++++++++++----------- 4 files changed, 17 insertions(+), 41 deletions(-)

diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h index 5ff1f19fd45c..0099dc116168 100644 --- a/arch/riscv/include/asm/mmu.h +++ b/arch/riscv/include/asm/mmu.h @@ -19,8 +19,6 @@ typedef struct { #ifdef CONFIG_SMP /* A local icache flush is needed before user execution can resume. */ cpumask_t icache_stale_mask;

•   /* A local tlb flush is needed before user execution can resume. */
  

•   cpumask_t tlb_stale_mask;
  

#endif } mm_context_t;

diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h index 907b9efd39a8..801019381dea 100644 --- a/arch/riscv/include/asm/tlbflush.h +++ b/arch/riscv/include/asm/tlbflush.h @@ -22,24 +22,6 @@ static inline void local_flush_tlb_page(unsigned long addr) { ALT_FLUSH_TLB_PAGE(__asm__ __volatile__ ("sfence.vma %0" : : "r" (addr) : "memory")); }

-static inline void local_flush_tlb_all_asid(unsigned long asid) -{

•   __asm__ __volatile__ ("sfence.vma x0, %0"
  

•                   :
  

•                   : "r" (asid)
  

•                   : "memory");
  

-}

-static inline void local_flush_tlb_page_asid(unsigned long addr,

•           unsigned long asid)
  

-{

•   __asm__ __volatile__ ("sfence.vma %0, %1"
  

•                   :
  

•                   : "r" (addr), "r" (asid)
  

•                   : "memory");
  

-}

#else /* CONFIG_MMU */ #define local_flush_tlb_all() do { } while (0) #define local_flush_tlb_page(addr) do { } while (0) diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c index 80ce9caba8d2..7acbfbd14557 100644 --- a/arch/riscv/mm/context.c +++ b/arch/riscv/mm/context.c @@ -196,16 +196,6 @@ static void set_mm_asid(struct mm_struct *mm, unsigned int cpu)

    if (need_flush_tlb)
            local_flush_tlb_all();

-#ifdef CONFIG_SMP

•   else {
  

•           cpumask_t *mask = &mm->context.tlb_stale_mask;
  

•           if (cpumask_test_cpu(cpu, mask)) {
  

•                   cpumask_clear_cpu(cpu, mask);
  

•                   local_flush_tlb_all_asid(cntx & asid_mask);
  

•           }
  

•   }
  

-#endif }

static void set_mm_noasid(struct mm_struct *mm) diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c index ce7dfc81bb3f..37ed760d007c 100644 --- a/arch/riscv/mm/tlbflush.c +++ b/arch/riscv/mm/tlbflush.c @@ -5,7 +5,23 @@ #include <linux/sched.h> #include <asm/sbi.h> #include <asm/mmu_context.h> -#include <asm/tlbflush.h>

+static inline void local_flush_tlb_all_asid(unsigned long asid) +{

•   __asm__ __volatile__ ("sfence.vma x0, %0"
  

•                   :
  

•                   : "r" (asid)
  

•                   : "memory");
  

+}

+static inline void local_flush_tlb_page_asid(unsigned long addr,

•           unsigned long asid)
  

+{

•   __asm__ __volatile__ ("sfence.vma %0, %1"
  

•                   :
  

•                   : "r" (addr), "r" (asid)
  

•                   : "memory");
  

+}

void flush_tlb_all(void) { @@ -15,7 +31,6 @@ void flush_tlb_all(void) static void __sbi_tlb_flush_range(struct mm_struct *mm, unsigned long start, unsigned long size, unsigned long stride) {

•   struct cpumask *pmask = &mm->context.tlb_stale_mask;
    struct cpumask *cmask = mm_cpumask(mm);
    unsigned int cpuid;
    bool broadcast;
  

@@ -29,15 +44,6 @@ static void __sbi_tlb_flush_range(struct mm_struct *mm, unsigned long start, if (static_branch_unlikely(&use_asid_allocator)) { unsigned long asid = atomic_long_read(&mm->context.id);

•           /*
  

•            * TLB will be immediately flushed on harts concurrently
  

•            * executing this MM context. TLB flush on other harts
  

•            * is deferred until this MM context migrates there.
  

•            */
  

•           cpumask_setall(pmask);
  

•           cpumask_clear_cpu(cpuid, pmask);
  

•           cpumask_andnot(pmask, pmask, cmask);
  

•           if (broadcast) {
                    sbi_remote_sfence_vma_asid(cmask, start, size, asid);
            } else if (size <= stride) {
  

-- 2.39.2