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Re: [Qemu-devel] [RFC v7 07/16] softmmu: Add helpers for a new slowpath
From: |
Alex Bennée |
Subject: |
Re: [Qemu-devel] [RFC v7 07/16] softmmu: Add helpers for a new slowpath |
Date: |
Thu, 11 Feb 2016 16:33:10 +0000 |
User-agent: |
mu4e 0.9.17; emacs 25.0.90.5 |
Alvise Rigo <address@hidden> writes:
> The new helpers rely on the legacy ones to perform the actual read/write.
>
> The LoadLink helper (helper_ldlink_name) prepares the way for the
> following StoreCond operation. It sets the linked address and the size
> of the access. The LoadLink helper also updates the TLB entry of the
> page involved in the LL/SC to all vCPUs by forcing a TLB flush, so that
> the following accesses made by all the vCPUs will follow the slow path.
>
> The StoreConditional helper (helper_stcond_name) returns 1 if the
> store has to fail due to a concurrent access to the same page by
> another vCPU. A 'concurrent access' can be a store made by *any* vCPU
> (although, some implementations allow stores made by the CPU that issued
> the LoadLink).
>
> Suggested-by: Jani Kokkonen <address@hidden>
> Suggested-by: Claudio Fontana <address@hidden>
> Signed-off-by: Alvise Rigo <address@hidden>
> ---
> cputlb.c | 3 ++
> include/qom/cpu.h | 5 ++
> softmmu_llsc_template.h | 133
> ++++++++++++++++++++++++++++++++++++++++++++++++
> softmmu_template.h | 12 +++++
> tcg/tcg.h | 31 +++++++++++
> 5 files changed, 184 insertions(+)
> create mode 100644 softmmu_llsc_template.h
>
> diff --git a/cputlb.c b/cputlb.c
> index f6fb161..ce6d720 100644
> --- a/cputlb.c
> +++ b/cputlb.c
> @@ -476,6 +476,8 @@ tb_page_addr_t get_page_addr_code(CPUArchState *env1,
> target_ulong addr)
>
> #define MMUSUFFIX _mmu
>
> +/* Generates LoadLink/StoreConditional helpers in softmmu_template.h */
> +#define GEN_EXCLUSIVE_HELPERS
> #define SHIFT 0
> #include "softmmu_template.h"
>
> @@ -488,6 +490,7 @@ tb_page_addr_t get_page_addr_code(CPUArchState *env1,
> target_ulong addr)
> #define SHIFT 3
> #include "softmmu_template.h"
> #undef MMUSUFFIX
> +#undef GEN_EXCLUSIVE_HELPERS
>
> #define MMUSUFFIX _cmmu
> #undef GETPC_ADJ
> diff --git a/include/qom/cpu.h b/include/qom/cpu.h
> index 682c81d..6f6c1c0 100644
> --- a/include/qom/cpu.h
> +++ b/include/qom/cpu.h
> @@ -351,10 +351,15 @@ struct CPUState {
> */
> bool throttle_thread_scheduled;
>
> + /* Used by the atomic insn translation backend. */
> + bool ll_sc_context;
> /* vCPU's exclusive addresses range.
> * The address is set to EXCLUSIVE_RESET_ADDR if the vCPU is not
> * in the middle of a LL/SC. */
> struct Range excl_protected_range;
> + /* Used to carry the SC result but also to flag a normal store access
> made
> + * by a stcond (see softmmu_template.h). */
> + bool excl_succeeded;
>
> /* Note that this is accessed at the start of every TB via a negative
> offset from AREG0. Leave this field at the end so as to make the
> diff --git a/softmmu_llsc_template.h b/softmmu_llsc_template.h
> new file mode 100644
> index 0000000..101f5e8
> --- /dev/null
> +++ b/softmmu_llsc_template.h
> @@ -0,0 +1,133 @@
> +/*
> + * Software MMU support (esclusive load/store operations)
> + *
> + * Generate helpers used by TCG for qemu_ldlink/stcond ops.
> + *
> + * Included from softmmu_template.h only.
> + *
> + * Copyright (c) 2015 Virtual Open Systems
> + *
> + * Authors:
> + * Alvise Rigo <address@hidden>
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see
> <http://www.gnu.org/licenses/>.
> + */
> +
> +/* This template does not generate together the le and be version, but only
> one
> + * of the two depending on whether BIGENDIAN_EXCLUSIVE_HELPERS has been set.
> + * The same nomenclature as softmmu_template.h is used for the exclusive
> + * helpers. */
> +
> +#ifdef BIGENDIAN_EXCLUSIVE_HELPERS
> +
> +#define helper_ldlink_name glue(glue(helper_be_ldlink, USUFFIX), MMUSUFFIX)
> +#define helper_stcond_name glue(glue(helper_be_stcond, SUFFIX), MMUSUFFIX)
> +#define helper_ld glue(glue(helper_be_ld, USUFFIX), MMUSUFFIX)
> +#define helper_st glue(glue(helper_be_st, SUFFIX), MMUSUFFIX)
> +
> +#else /* LE helpers + 8bit helpers (generated only once for both LE end BE)
> */
> +
> +#if DATA_SIZE > 1
> +#define helper_ldlink_name glue(glue(helper_le_ldlink, USUFFIX), MMUSUFFIX)
> +#define helper_stcond_name glue(glue(helper_le_stcond, SUFFIX), MMUSUFFIX)
> +#define helper_ld glue(glue(helper_le_ld, USUFFIX), MMUSUFFIX)
> +#define helper_st glue(glue(helper_le_st, SUFFIX), MMUSUFFIX)
> +#else /* DATA_SIZE <= 1 */
> +#define helper_ldlink_name glue(glue(helper_ret_ldlink, USUFFIX), MMUSUFFIX)
> +#define helper_stcond_name glue(glue(helper_ret_stcond, SUFFIX), MMUSUFFIX)
> +#define helper_ld glue(glue(helper_ret_ld, USUFFIX), MMUSUFFIX)
> +#define helper_st glue(glue(helper_ret_st, SUFFIX), MMUSUFFIX)
> +#endif
> +
> +#endif
> +
> +WORD_TYPE helper_ldlink_name(CPUArchState *env, target_ulong addr,
> + TCGMemOpIdx oi, uintptr_t retaddr)
> +{
> + WORD_TYPE ret;
> + int index;
> + CPUState *cpu, *this = ENV_GET_CPU(env);
I'd rename this to this_cpu and move the *cpu definition to inside the
if {} where it is used so no confusion occurs.
> + CPUClass *cc = CPU_GET_CLASS(this);
> + hwaddr hw_addr;
> + unsigned mmu_idx = get_mmuidx(oi);
> +
> + /* Use the proper load helper from cpu_ldst.h */
> + ret = helper_ld(env, addr, oi, retaddr);
> +
> + index = (addr >> TARGET_PAGE_BITS) & (CPU_TLB_SIZE - 1);
> +
> + /* hw_addr = hwaddr of the page (i.e. section->mr->ram_addr + xlat)
> + * plus the offset (i.e. addr & ~TARGET_PAGE_MASK) */
> + hw_addr = (env->iotlb[mmu_idx][index].addr & TARGET_PAGE_MASK) + addr;
> + if (likely(!(env->tlb_table[mmu_idx][index].addr_read & TLB_MMIO))) {
> + /* If all the vCPUs have the EXCL bit set for this page there is no
> need
> + * to request any flush. */
> + if (!cpu_physical_memory_is_excl(hw_addr)) {
> + cpu_physical_memory_set_excl(hw_addr);
> + CPU_FOREACH(cpu) {
> + if (current_cpu != cpu) {
Why use current_cpu is we have this_cpu? I'd argue the check should use
what we've been passed over global (and future TLS value).
> + tlb_flush(cpu, 1);
> + }
> + }
> + }
> + } else {
> + hw_error("EXCL accesses to MMIO regions not supported yet.");
> + }
> +
> + cc->cpu_set_excl_protected_range(this, hw_addr, DATA_SIZE);
> +
> + /* For this vCPU, just update the TLB entry, no need to flush. */
> + env->tlb_table[mmu_idx][index].addr_write |= TLB_EXCL;
> +
> + /* From now on we are in LL/SC context */
> + this->ll_sc_context = true;
> +
> + return ret;
> +}
> +
> +WORD_TYPE helper_stcond_name(CPUArchState *env, target_ulong addr,
> + DATA_TYPE val, TCGMemOpIdx oi,
> + uintptr_t retaddr)
> +{
> + WORD_TYPE ret;
> + CPUState *cpu = ENV_GET_CPU(env);
> +
> + if (!cpu->ll_sc_context) {
> + ret = 1;
> + } else {
> + /* We set it preventively to true to distinguish the following legacy
> + * access as one made by the store conditional wrapper. If the store
> + * conditional does not succeed, the value will be set to 0.*/
> + cpu->excl_succeeded = true;
> + helper_st(env, addr, val, oi, retaddr);
> +
> + if (cpu->excl_succeeded) {
> + ret = 0;
> + } else {
> + ret = 1;
> + }
> + }
> +
> + /* Unset LL/SC context */
> + cpu->ll_sc_context = false;
> + cpu->excl_succeeded = false;
> + cpu->excl_protected_range.begin = EXCLUSIVE_RESET_ADDR;
> +
> + return ret;
> +}
> +
> +#undef helper_ldlink_name
> +#undef helper_stcond_name
> +#undef helper_ld
> +#undef helper_st
> diff --git a/softmmu_template.h b/softmmu_template.h
> index 6279437..4332db2 100644
> --- a/softmmu_template.h
> +++ b/softmmu_template.h
> @@ -622,6 +622,18 @@ void probe_write(CPUArchState *env, target_ulong addr,
> int mmu_idx,
> #endif
> #endif /* !defined(SOFTMMU_CODE_ACCESS) */
>
> +#ifdef GEN_EXCLUSIVE_HELPERS
> +
> +#if DATA_SIZE > 1 /* The 8-bit helpers are generate along with LE helpers */
> +#define BIGENDIAN_EXCLUSIVE_HELPERS
> +#include "softmmu_llsc_template.h"
> +#undef BIGENDIAN_EXCLUSIVE_HELPERS
> +#endif
> +
> +#include "softmmu_llsc_template.h"
> +
> +#endif /* !defined(GEN_EXCLUSIVE_HELPERS) */
> +
> #undef READ_ACCESS_TYPE
> #undef SHIFT
> #undef DATA_TYPE
> diff --git a/tcg/tcg.h b/tcg/tcg.h
> index a696922..3e050a4 100644
> --- a/tcg/tcg.h
> +++ b/tcg/tcg.h
> @@ -968,6 +968,21 @@ tcg_target_ulong helper_be_ldul_mmu(CPUArchState *env,
> target_ulong addr,
> TCGMemOpIdx oi, uintptr_t retaddr);
> uint64_t helper_be_ldq_mmu(CPUArchState *env, target_ulong addr,
> TCGMemOpIdx oi, uintptr_t retaddr);
> +/* Exclusive variants */
> +tcg_target_ulong helper_ret_ldlinkub_mmu(CPUArchState *env, target_ulong
> addr,
> + TCGMemOpIdx oi, uintptr_t
> retaddr);
> +tcg_target_ulong helper_le_ldlinkuw_mmu(CPUArchState *env, target_ulong addr,
> + TCGMemOpIdx oi, uintptr_t
> retaddr);
> +tcg_target_ulong helper_le_ldlinkul_mmu(CPUArchState *env, target_ulong addr,
> + TCGMemOpIdx oi, uintptr_t
> retaddr);
> +uint64_t helper_le_ldlinkq_mmu(CPUArchState *env, target_ulong addr,
> + TCGMemOpIdx oi, uintptr_t
> retaddr);
> +tcg_target_ulong helper_be_ldlinkuw_mmu(CPUArchState *env, target_ulong addr,
> + TCGMemOpIdx oi, uintptr_t
> retaddr);
> +tcg_target_ulong helper_be_ldlinkul_mmu(CPUArchState *env, target_ulong addr,
> + TCGMemOpIdx oi, uintptr_t
> retaddr);
> +uint64_t helper_be_ldlinkq_mmu(CPUArchState *env, target_ulong addr,
> + TCGMemOpIdx oi, uintptr_t
> retaddr);
>
> /* Value sign-extended to tcg register size. */
> tcg_target_ulong helper_ret_ldsb_mmu(CPUArchState *env, target_ulong addr,
> @@ -1010,6 +1025,22 @@ uint32_t helper_be_ldl_cmmu(CPUArchState *env,
> target_ulong addr,
> TCGMemOpIdx oi, uintptr_t retaddr);
> uint64_t helper_be_ldq_cmmu(CPUArchState *env, target_ulong addr,
> TCGMemOpIdx oi, uintptr_t retaddr);
> +/* Exclusive variants */
> +tcg_target_ulong helper_ret_stcondb_mmu(CPUArchState *env, target_ulong addr,
> + uint8_t val, TCGMemOpIdx oi, uintptr_t retaddr);
> +tcg_target_ulong helper_le_stcondw_mmu(CPUArchState *env, target_ulong addr,
> + uint16_t val, TCGMemOpIdx oi, uintptr_t retaddr);
> +tcg_target_ulong helper_le_stcondl_mmu(CPUArchState *env, target_ulong addr,
> + uint32_t val, TCGMemOpIdx oi, uintptr_t retaddr);
> +uint64_t helper_le_stcondq_mmu(CPUArchState *env, target_ulong addr,
> + uint64_t val, TCGMemOpIdx oi, uintptr_t retaddr);
> +tcg_target_ulong helper_be_stcondw_mmu(CPUArchState *env, target_ulong addr,
> + uint16_t val, TCGMemOpIdx oi, uintptr_t retaddr);
> +tcg_target_ulong helper_be_stcondl_mmu(CPUArchState *env, target_ulong addr,
> + uint32_t val, TCGMemOpIdx oi, uintptr_t retaddr);
> +uint64_t helper_be_stcondq_mmu(CPUArchState *env, target_ulong addr,
> + uint64_t val, TCGMemOpIdx oi, uintptr_t retaddr);
> +
>
> /* Temporary aliases until backends are converted. */
> #ifdef TARGET_WORDS_BIGENDIAN
--
Alex Bennée
- Re: [Qemu-devel] [RFC v7 07/16] softmmu: Add helpers for a new slowpath,
Alex Bennée <=