On 8/9/19, 8:30 PM, "Anup Patel" <a...@brainfault.org> wrote:
On Sat, Aug 10, 2019 at 7:13 AM Atish Patra <atish.pa...@wdc.com> wrote: > > In RISC-V, tlb flush happens via SBI which is expensive. > If the target cpumask contains a local hartid, some cost > can be saved by issuing a local tlb flush as we do that > in OpenSBI anyways. > > Signed-off-by: Atish Patra <atish.pa...@wdc.com> > --- > arch/riscv/include/asm/tlbflush.h | 33 +++++++++++++++++++++++++++---- > 1 file changed, 29 insertions(+), 4 deletions(-) > > diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h > index 687dd19735a7..b32ba4fa5888 100644 > --- a/arch/riscv/include/asm/tlbflush.h > +++ b/arch/riscv/include/asm/tlbflush.h > @@ -8,6 +8,7 @@ > #define _ASM_RISCV_TLBFLUSH_H > > #include <linux/mm_types.h> > +#include <linux/sched.h> > #include <asm/smp.h> > > /* > @@ -46,14 +47,38 @@ static inline void remote_sfence_vma(struct cpumask *cmask, unsigned long start, > unsigned long size) > { > struct cpumask hmask; > + struct cpumask tmask; > + int cpuid = smp_processor_id(); > > cpumask_clear(&hmask); > - riscv_cpuid_to_hartid_mask(cmask, &hmask); > - sbi_remote_sfence_vma(hmask.bits, start, size); > + cpumask_clear(&tmask); > + > + if (cmask) > + cpumask_copy(&tmask, cmask); > + else > + cpumask_copy(&tmask, cpu_online_mask); This can be further simplified. We can totally avoid tmask, cpumask_copy(), and cpumask_clear() by directly updating hmask. Ahh yes. Thanks for pointing out. In addition to this patch, we should also handle the case of empty hart mask in OpenSBI. Yes. I have few other fixes as well (around fifo race condition and local flushing in OpenSBI). I will send them soon. Regards, Atish > + > + if (cpumask_test_cpu(cpuid, &tmask)) { > + /* Save trap cost by issuing a local tlb flush here */ > + if ((start == 0 && size == -1) || (size > PAGE_SIZE)) > + local_flush_tlb_all(); > + else if (size == PAGE_SIZE) > + local_flush_tlb_page(start); > + cpumask_clear_cpu(cpuid, &tmask); > + } else if (cpumask_empty(&tmask)) { > + /* cpumask is empty. So just do a local flush */ > + local_flush_tlb_all(); > + return; > + } > + > + if (!cpumask_empty(&tmask)) { > + riscv_cpuid_to_hartid_mask(&tmask, &hmask); > + sbi_remote_sfence_vma(hmask.bits, start, size); > + } > } > > -#define flush_tlb_all() sbi_remote_sfence_vma(NULL, 0, -1) > -#define flush_tlb_page(vma, addr) flush_tlb_range(vma, addr, 0) > +#define flush_tlb_all() remote_sfence_vma(NULL, 0, -1) > +#define flush_tlb_page(vma, addr) flush_tlb_range(vma, addr, (addr) + PAGE_SIZE) > #define flush_tlb_range(vma, start, end) \ > remote_sfence_vma(mm_cpumask((vma)->vm_mm), start, (end) - (start)) > #define flush_tlb_mm(mm) \ > -- > 2.21.0 > > > _______________________________________________ > linux-riscv mailing list > linux-ri...@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv Regards, Anup