| Message ID | 1454059965-23402-14-git-send-email-a.rigo@virtualopensystems.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Alvise Rigo <a.rigo@virtualopensystems.com> writes: > Add a circular buffer to store the hw addresses used in the last > EXCLUSIVE_HISTORY_LEN exclusive accesses. > > When an address is pop'ed from the buffer, its page will be set as not > exclusive. In this way, we avoid: > - frequent set/unset of a page (causing frequent flushes as well) > - the possibility to forget the EXCL bit set. Why was this a possibility before? Shouldn't that be tackled in the patch that introduced it? > > Suggested-by: Jani Kokkonen <jani.kokkonen@huawei.com> > Suggested-by: Claudio Fontana <claudio.fontana@huawei.com> > Signed-off-by: Alvise Rigo <a.rigo@virtualopensystems.com> > --- > cputlb.c | 29 +++++++++++++++++++---------- > exec.c | 19 +++++++++++++++++++ > include/qom/cpu.h | 8 ++++++++ > softmmu_llsc_template.h | 1 + > vl.c | 3 +++ > 5 files changed, 50 insertions(+), 10 deletions(-) > > diff --git a/cputlb.c b/cputlb.c > index 06ce2da..f3c4d97 100644 > --- a/cputlb.c > +++ b/cputlb.c > @@ -395,16 +395,6 @@ void tlb_set_page_with_attrs(CPUState *cpu, target_ulong vaddr, > env->tlb_v_table[mmu_idx][vidx] = *te; > env->iotlb_v[mmu_idx][vidx] = env->iotlb[mmu_idx][index]; > > - if (unlikely(!(te->addr_write & TLB_MMIO) && (te->addr_write & TLB_EXCL))) { > - /* We are removing an exclusive entry, set the page to dirty. This > - * is not be necessary if the vCPU has performed both SC and LL. */ > - hwaddr hw_addr = (env->iotlb[mmu_idx][index].addr & TARGET_PAGE_MASK) + > - (te->addr_write & TARGET_PAGE_MASK); > - if (!cpu->ll_sc_context) { > - cpu_physical_memory_unset_excl(hw_addr); > - } > - } > - Errm is this right? I got confused reviewing 8/16 because my final tree didn't have this code. I'm not sure the adding of history obviates the need to clear the exclusive flag? > /* refill the tlb */ > env->iotlb[mmu_idx][index].addr = iotlb - vaddr; > env->iotlb[mmu_idx][index].attrs = attrs; > @@ -517,6 +507,25 @@ static inline bool lookup_and_reset_cpus_ll_addr(hwaddr addr, hwaddr size) > return ret; > } > > +extern CPUExclusiveHistory excl_history; > +static inline void excl_history_put_addr(hwaddr addr) > +{ > + hwaddr last; > + > + /* Calculate the index of the next exclusive address */ > + excl_history.last_idx = (excl_history.last_idx + 1) % excl_history.length; > + > + last = excl_history.c_array[excl_history.last_idx]; > + > + /* Unset EXCL bit of the oldest entry */ > + if (last != EXCLUSIVE_RESET_ADDR) { > + cpu_physical_memory_unset_excl(last); > + } > + > + /* Add a new address, overwriting the oldest one */ > + excl_history.c_array[excl_history.last_idx] = addr & TARGET_PAGE_MASK; > +} > + > #define MMUSUFFIX _mmu > > /* Generates LoadLink/StoreConditional helpers in softmmu_template.h */ > diff --git a/exec.c b/exec.c > index 51f366d..2e123f1 100644 > --- a/exec.c > +++ b/exec.c > @@ -177,6 +177,25 @@ struct CPUAddressSpace { > MemoryListener tcg_as_listener; > }; > > +/* Exclusive memory support */ > +CPUExclusiveHistory excl_history; > +void cpu_exclusive_history_init(void) > +{ > + /* Initialize exclusive history for atomic instruction handling. */ > + if (tcg_enabled()) { > + g_assert(EXCLUSIVE_HISTORY_CPU_LEN * max_cpus <= UINT16_MAX); > + excl_history.length = EXCLUSIVE_HISTORY_CPU_LEN * max_cpus; > + excl_history.c_array = g_malloc(excl_history.length * sizeof(hwaddr)); > + memset(excl_history.c_array, -1, excl_history.length * sizeof(hwaddr)); > + } > +} > + > +void cpu_exclusive_history_free(void) > +{ > + if (tcg_enabled()) { > + g_free(excl_history.c_array); > + } > +} > #endif > > #if !defined(CONFIG_USER_ONLY) > diff --git a/include/qom/cpu.h b/include/qom/cpu.h > index 6f6c1c0..0452fd0 100644 > --- a/include/qom/cpu.h > +++ b/include/qom/cpu.h > @@ -227,7 +227,15 @@ struct kvm_run; > #define TB_JMP_CACHE_SIZE (1 << TB_JMP_CACHE_BITS) > > /* Atomic insn translation TLB support. */ > +typedef struct CPUExclusiveHistory { > + uint16_t last_idx; /* index of last insertion */ > + uint16_t length; /* history's length, it depends on smp_cpus */ > + hwaddr *c_array; /* history's circular array */ > +} CPUExclusiveHistory; > #define EXCLUSIVE_RESET_ADDR ULLONG_MAX > +#define EXCLUSIVE_HISTORY_CPU_LEN 256 > +void cpu_exclusive_history_init(void); > +void cpu_exclusive_history_free(void); > > /** > * CPUState: > diff --git a/softmmu_llsc_template.h b/softmmu_llsc_template.h > index b4712ba..b4e7f9d 100644 > --- a/softmmu_llsc_template.h > +++ b/softmmu_llsc_template.h > @@ -75,6 +75,7 @@ WORD_TYPE helper_ldlink_name(CPUArchState *env, target_ulong addr, > * to request any flush. */ > if (!cpu_physical_memory_is_excl(hw_addr)) { > cpu_physical_memory_set_excl(hw_addr); > + excl_history_put_addr(hw_addr); > CPU_FOREACH(cpu) { > if (current_cpu != cpu) { > tlb_flush(cpu, 1); > diff --git a/vl.c b/vl.c > index f043009..b22d99b 100644 > --- a/vl.c > +++ b/vl.c > @@ -547,6 +547,7 @@ static void res_free(void) > { > g_free(boot_splash_filedata); > boot_splash_filedata = NULL; > + cpu_exclusive_history_free(); > } > > static int default_driver_check(void *opaque, QemuOpts *opts, Error **errp) > @@ -4322,6 +4323,8 @@ int main(int argc, char **argv, char **envp) > > configure_accelerator(current_machine); > > + cpu_exclusive_history_init(); > + > if (qtest_chrdev) { > qtest_init(qtest_chrdev, qtest_log, &error_fatal); > } -- Alex Bennée
On Tue, Feb 16, 2016 at 6:07 PM, Alex Bennée <alex.bennee@linaro.org> wrote: > > Alvise Rigo <a.rigo@virtualopensystems.com> writes: > >> Add a circular buffer to store the hw addresses used in the last >> EXCLUSIVE_HISTORY_LEN exclusive accesses. >> >> When an address is pop'ed from the buffer, its page will be set as not >> exclusive. In this way, we avoid: >> - frequent set/unset of a page (causing frequent flushes as well) >> - the possibility to forget the EXCL bit set. > > Why was this a possibility before? Shouldn't that be tackled in the > patch that introduced it? Yes and no. The problem happens for instance when a LL will not be followed by the SC. In this situation, the flag will be set for the page, but might remain set for the rest of the execution (unless a complete LL/SC in performed later on in the same guest page). > >> >> Suggested-by: Jani Kokkonen <jani.kokkonen@huawei.com> >> Suggested-by: Claudio Fontana <claudio.fontana@huawei.com> >> Signed-off-by: Alvise Rigo <a.rigo@virtualopensystems.com> >> --- >> cputlb.c | 29 +++++++++++++++++++---------- >> exec.c | 19 +++++++++++++++++++ >> include/qom/cpu.h | 8 ++++++++ >> softmmu_llsc_template.h | 1 + >> vl.c | 3 +++ >> 5 files changed, 50 insertions(+), 10 deletions(-) >> >> diff --git a/cputlb.c b/cputlb.c >> index 06ce2da..f3c4d97 100644 >> --- a/cputlb.c >> +++ b/cputlb.c >> @@ -395,16 +395,6 @@ void tlb_set_page_with_attrs(CPUState *cpu, target_ulong vaddr, >> env->tlb_v_table[mmu_idx][vidx] = *te; >> env->iotlb_v[mmu_idx][vidx] = env->iotlb[mmu_idx][index]; >> >> - if (unlikely(!(te->addr_write & TLB_MMIO) && (te->addr_write & TLB_EXCL))) { >> - /* We are removing an exclusive entry, set the page to dirty. This >> - * is not be necessary if the vCPU has performed both SC and LL. */ >> - hwaddr hw_addr = (env->iotlb[mmu_idx][index].addr & TARGET_PAGE_MASK) + >> - (te->addr_write & TARGET_PAGE_MASK); >> - if (!cpu->ll_sc_context) { >> - cpu_physical_memory_unset_excl(hw_addr); >> - } >> - } >> - > > Errm is this right? I got confused reviewing 8/16 because my final tree > didn't have this code. I'm not sure the adding of history obviates the > need to clear the exclusive flag? We will clear it adding a new item to the history. When an entry is added, the oldest is removed and cleaned, solving the problem mentioned above. Thank you, alvise > >> /* refill the tlb */ >> env->iotlb[mmu_idx][index].addr = iotlb - vaddr; >> env->iotlb[mmu_idx][index].attrs = attrs; >> @@ -517,6 +507,25 @@ static inline bool lookup_and_reset_cpus_ll_addr(hwaddr addr, hwaddr size) >> return ret; >> } >> >> +extern CPUExclusiveHistory excl_history; >> +static inline void excl_history_put_addr(hwaddr addr) >> +{ >> + hwaddr last; >> + >> + /* Calculate the index of the next exclusive address */ >> + excl_history.last_idx = (excl_history.last_idx + 1) % excl_history.length; >> + >> + last = excl_history.c_array[excl_history.last_idx]; >> + >> + /* Unset EXCL bit of the oldest entry */ >> + if (last != EXCLUSIVE_RESET_ADDR) { >> + cpu_physical_memory_unset_excl(last); >> + } >> + >> + /* Add a new address, overwriting the oldest one */ >> + excl_history.c_array[excl_history.last_idx] = addr & TARGET_PAGE_MASK; >> +} >> + >> #define MMUSUFFIX _mmu >> >> /* Generates LoadLink/StoreConditional helpers in softmmu_template.h */ >> diff --git a/exec.c b/exec.c >> index 51f366d..2e123f1 100644 >> --- a/exec.c >> +++ b/exec.c >> @@ -177,6 +177,25 @@ struct CPUAddressSpace { >> MemoryListener tcg_as_listener; >> }; >> >> +/* Exclusive memory support */ >> +CPUExclusiveHistory excl_history; >> +void cpu_exclusive_history_init(void) >> +{ >> + /* Initialize exclusive history for atomic instruction handling. */ >> + if (tcg_enabled()) { >> + g_assert(EXCLUSIVE_HISTORY_CPU_LEN * max_cpus <= UINT16_MAX); >> + excl_history.length = EXCLUSIVE_HISTORY_CPU_LEN * max_cpus; >> + excl_history.c_array = g_malloc(excl_history.length * sizeof(hwaddr)); >> + memset(excl_history.c_array, -1, excl_history.length * sizeof(hwaddr)); >> + } >> +} >> + >> +void cpu_exclusive_history_free(void) >> +{ >> + if (tcg_enabled()) { >> + g_free(excl_history.c_array); >> + } >> +} >> #endif >> >> #if !defined(CONFIG_USER_ONLY) >> diff --git a/include/qom/cpu.h b/include/qom/cpu.h >> index 6f6c1c0..0452fd0 100644 >> --- a/include/qom/cpu.h >> +++ b/include/qom/cpu.h >> @@ -227,7 +227,15 @@ struct kvm_run; >> #define TB_JMP_CACHE_SIZE (1 << TB_JMP_CACHE_BITS) >> >> /* Atomic insn translation TLB support. */ >> +typedef struct CPUExclusiveHistory { >> + uint16_t last_idx; /* index of last insertion */ >> + uint16_t length; /* history's length, it depends on smp_cpus */ >> + hwaddr *c_array; /* history's circular array */ >> +} CPUExclusiveHistory; >> #define EXCLUSIVE_RESET_ADDR ULLONG_MAX >> +#define EXCLUSIVE_HISTORY_CPU_LEN 256 >> +void cpu_exclusive_history_init(void); >> +void cpu_exclusive_history_free(void); >> >> /** >> * CPUState: >> diff --git a/softmmu_llsc_template.h b/softmmu_llsc_template.h >> index b4712ba..b4e7f9d 100644 >> --- a/softmmu_llsc_template.h >> +++ b/softmmu_llsc_template.h >> @@ -75,6 +75,7 @@ WORD_TYPE helper_ldlink_name(CPUArchState *env, target_ulong addr, >> * to request any flush. */ >> if (!cpu_physical_memory_is_excl(hw_addr)) { >> cpu_physical_memory_set_excl(hw_addr); >> + excl_history_put_addr(hw_addr); >> CPU_FOREACH(cpu) { >> if (current_cpu != cpu) { >> tlb_flush(cpu, 1); >> diff --git a/vl.c b/vl.c >> index f043009..b22d99b 100644 >> --- a/vl.c >> +++ b/vl.c >> @@ -547,6 +547,7 @@ static void res_free(void) >> { >> g_free(boot_splash_filedata); >> boot_splash_filedata = NULL; >> + cpu_exclusive_history_free(); >> } >> >> static int default_driver_check(void *opaque, QemuOpts *opts, Error **errp) >> @@ -4322,6 +4323,8 @@ int main(int argc, char **argv, char **envp) >> >> configure_accelerator(current_machine); >> >> + cpu_exclusive_history_init(); >> + >> if (qtest_chrdev) { >> qtest_init(qtest_chrdev, qtest_log, &error_fatal); >> } > > > -- > Alex Bennée
diff --git a/cputlb.c b/cputlb.c index 06ce2da..f3c4d97 100644 --- a/cputlb.c +++ b/cputlb.c @@ -395,16 +395,6 @@ void tlb_set_page_with_attrs(CPUState *cpu, target_ulong vaddr, env->tlb_v_table[mmu_idx][vidx] = *te; env->iotlb_v[mmu_idx][vidx] = env->iotlb[mmu_idx][index]; - if (unlikely(!(te->addr_write & TLB_MMIO) && (te->addr_write & TLB_EXCL))) { - /* We are removing an exclusive entry, set the page to dirty. This - * is not be necessary if the vCPU has performed both SC and LL. */ - hwaddr hw_addr = (env->iotlb[mmu_idx][index].addr & TARGET_PAGE_MASK) + - (te->addr_write & TARGET_PAGE_MASK); - if (!cpu->ll_sc_context) { - cpu_physical_memory_unset_excl(hw_addr); - } - } - /* refill the tlb */ env->iotlb[mmu_idx][index].addr = iotlb - vaddr; env->iotlb[mmu_idx][index].attrs = attrs; @@ -517,6 +507,25 @@ static inline bool lookup_and_reset_cpus_ll_addr(hwaddr addr, hwaddr size) return ret; } +extern CPUExclusiveHistory excl_history; +static inline void excl_history_put_addr(hwaddr addr) +{ + hwaddr last; + + /* Calculate the index of the next exclusive address */ + excl_history.last_idx = (excl_history.last_idx + 1) % excl_history.length; + + last = excl_history.c_array[excl_history.last_idx]; + + /* Unset EXCL bit of the oldest entry */ + if (last != EXCLUSIVE_RESET_ADDR) { + cpu_physical_memory_unset_excl(last); + } + + /* Add a new address, overwriting the oldest one */ + excl_history.c_array[excl_history.last_idx] = addr & TARGET_PAGE_MASK; +} + #define MMUSUFFIX _mmu /* Generates LoadLink/StoreConditional helpers in softmmu_template.h */ diff --git a/exec.c b/exec.c index 51f366d..2e123f1 100644 --- a/exec.c +++ b/exec.c @@ -177,6 +177,25 @@ struct CPUAddressSpace { MemoryListener tcg_as_listener; }; +/* Exclusive memory support */ +CPUExclusiveHistory excl_history; +void cpu_exclusive_history_init(void) +{ + /* Initialize exclusive history for atomic instruction handling. */ + if (tcg_enabled()) { + g_assert(EXCLUSIVE_HISTORY_CPU_LEN * max_cpus <= UINT16_MAX); + excl_history.length = EXCLUSIVE_HISTORY_CPU_LEN * max_cpus; + excl_history.c_array = g_malloc(excl_history.length * sizeof(hwaddr)); + memset(excl_history.c_array, -1, excl_history.length * sizeof(hwaddr)); + } +} + +void cpu_exclusive_history_free(void) +{ + if (tcg_enabled()) { + g_free(excl_history.c_array); + } +} #endif #if !defined(CONFIG_USER_ONLY) diff --git a/include/qom/cpu.h b/include/qom/cpu.h index 6f6c1c0..0452fd0 100644 --- a/include/qom/cpu.h +++ b/include/qom/cpu.h @@ -227,7 +227,15 @@ struct kvm_run; #define TB_JMP_CACHE_SIZE (1 << TB_JMP_CACHE_BITS) /* Atomic insn translation TLB support. */ +typedef struct CPUExclusiveHistory { + uint16_t last_idx; /* index of last insertion */ + uint16_t length; /* history's length, it depends on smp_cpus */ + hwaddr *c_array; /* history's circular array */ +} CPUExclusiveHistory; #define EXCLUSIVE_RESET_ADDR ULLONG_MAX +#define EXCLUSIVE_HISTORY_CPU_LEN 256 +void cpu_exclusive_history_init(void); +void cpu_exclusive_history_free(void); /** * CPUState: diff --git a/softmmu_llsc_template.h b/softmmu_llsc_template.h index b4712ba..b4e7f9d 100644 --- a/softmmu_llsc_template.h +++ b/softmmu_llsc_template.h @@ -75,6 +75,7 @@ WORD_TYPE helper_ldlink_name(CPUArchState *env, target_ulong addr, * to request any flush. */ if (!cpu_physical_memory_is_excl(hw_addr)) { cpu_physical_memory_set_excl(hw_addr); + excl_history_put_addr(hw_addr); CPU_FOREACH(cpu) { if (current_cpu != cpu) { tlb_flush(cpu, 1); diff --git a/vl.c b/vl.c index f043009..b22d99b 100644 --- a/vl.c +++ b/vl.c @@ -547,6 +547,7 @@ static void res_free(void) { g_free(boot_splash_filedata); boot_splash_filedata = NULL; + cpu_exclusive_history_free(); } static int default_driver_check(void *opaque, QemuOpts *opts, Error **errp) @@ -4322,6 +4323,8 @@ int main(int argc, char **argv, char **envp) configure_accelerator(current_machine); + cpu_exclusive_history_init(); + if (qtest_chrdev) { qtest_init(qtest_chrdev, qtest_log, &error_fatal); }
Add a circular buffer to store the hw addresses used in the last EXCLUSIVE_HISTORY_LEN exclusive accesses. When an address is pop'ed from the buffer, its page will be set as not exclusive. In this way, we avoid: - frequent set/unset of a page (causing frequent flushes as well) - the possibility to forget the EXCL bit set. Suggested-by: Jani Kokkonen <jani.kokkonen@huawei.com> Suggested-by: Claudio Fontana <claudio.fontana@huawei.com> Signed-off-by: Alvise Rigo <a.rigo@virtualopensystems.com> --- cputlb.c | 29 +++++++++++++++++++---------- exec.c | 19 +++++++++++++++++++ include/qom/cpu.h | 8 ++++++++ softmmu_llsc_template.h | 1 + vl.c | 3 +++ 5 files changed, 50 insertions(+), 10 deletions(-)