On Mon, Jan 22, 2024 at 10:42 AM Peter Maydell <peter.mayd...@linaro.org> wrote: > > On Fri, 19 Jan 2024 at 20:47, Max Filippov <jcmvb...@gmail.com> wrote: > > > > Whether TLB ways 5 and 6 are variable is not a property of the TLB > > instance or a TLB entry instance, it's a property of the xtensa core > > configuration. > > Remove 'varway56' field from the xtensa_tlb structure and remove > > 'variable' field from the xtensa_tlb_entry structure. Add > > 'tlb_variable_way' array to the XtensaConfig and use it instead of > > removed fields. > > > > Signed-off-by: Max Filippov <jcmvb...@gmail.com> > > --- > > target/xtensa/cpu.h | 3 +-- > > target/xtensa/mmu_helper.c | 38 ++++++++++-------------------------- > > target/xtensa/overlay_tool.h | 15 ++++++++++++-- > > 3 files changed, 24 insertions(+), 32 deletions(-) > > > > diff --git a/target/xtensa/cpu.h b/target/xtensa/cpu.h > > index 497325466397..24d3f15ea1bf 100644 > > --- a/target/xtensa/cpu.h > > +++ b/target/xtensa/cpu.h > > @@ -316,13 +316,11 @@ typedef struct xtensa_tlb_entry { > > uint32_t paddr; > > uint8_t asid; > > uint8_t attr; > > - bool variable; > > } xtensa_tlb_entry; > > > > typedef struct xtensa_tlb { > > unsigned nways; > > const unsigned way_size[10]; > > - bool varway56; > > unsigned nrefillentries; > > } xtensa_tlb; > > > > @@ -493,6 +491,7 @@ typedef struct XtensaConfig { > > > > xtensa_tlb itlb; > > xtensa_tlb dtlb; > > + bool tlb_variable_way[16]; > > > > uint32_t mpu_align; > > unsigned n_mpu_fg_segments; > > diff --git a/target/xtensa/mmu_helper.c b/target/xtensa/mmu_helper.c > > index d9f845e7fb6f..414c2f5ef669 100644 > > --- a/target/xtensa/mmu_helper.c > > +++ b/target/xtensa/mmu_helper.c > > @@ -105,23 +105,19 @@ static uint32_t xtensa_tlb_get_addr_mask(const > > CPUXtensaState *env, > > bool dtlb, uint32_t way) > > { > > if (xtensa_option_enabled(env->config, XTENSA_OPTION_MMU)) { > > - bool varway56 = dtlb ? > > - env->config->dtlb.varway56 : > > - env->config->itlb.varway56; > > - > > switch (way) { > > case 4: > > return 0xfff00000 << get_page_size(env, dtlb, way) * 2; > > > > case 5: > > - if (varway56) { > > + if (env->config->tlb_variable_way[5]) { > > return 0xf8000000 << get_page_size(env, dtlb, way); > > } else { > > return 0xf8000000; > > } > > > > case 6: > > - if (varway56) { > > + if (env->config->tlb_variable_way[6]) { > > return 0xf0000000 << (1 - get_page_size(env, dtlb, way)); > > } else { > > return 0xf0000000; > > So we now have a tlb_variable_way bool for all 16 possible > ways, but the code actually only checks it for ways 5 and 6.
xtensa_tlb_set_entry checks this for all possible ways. I would say that this is an unfortunate definition of MMU in the xtensa ISA book that uses the variability of the ways 5/6 as a discriminator between MMUv2 and MMUv3. > Should we have an assertion somewhere that the config > doesn't try to set it on ways where it has no effect ? > Or is there actually a generic behaviour that would make > sense for eg "way 3 is variable-way" that we just don't > currently implement? We currently use the TLB structure to implement the following xtensa memory management options: cacheattr, region protection, region translation, MMUv2 and MMUv3. First three only have one variable way, in MMUv2 all ways except 5 and 6 are variable and in MMUv3 all ways are variable. QEMU supports all of it and tlb_variable_way is set properly in all of these cases. > > @@ -150,11 +146,8 @@ static uint32_t get_vpn_mask(const CPUXtensaState > > *env, bool dtlb, uint32_t way) > > return xtensa_tlb_get_addr_mask(env, dtlb, way) << 2; > > } else if (way <= 6) { > > uint32_t mask = xtensa_tlb_get_addr_mask(env, dtlb, way); > > - bool varway56 = dtlb ? > > - env->config->dtlb.varway56 : > > - env->config->itlb.varway56; > > > > - if (varway56) { > > + if (env->config->tlb_variable_way[5]) { > > return mask << (way == 5 ? 2 : 3); > > } else { > > return mask << 1; > > This doesn't look right -- this branch of the if-else deals > with way == 5 and way == 6, but we're only looking at > tlb_variable_way[5]. Yeah, that's MMUv2 vs MMUv3 check, again. > > @@ -172,10 +165,6 @@ static void split_tlb_entry_spec_way(const > > CPUXtensaState *env, uint32_t v, > > bool dtlb, uint32_t *vpn, > > uint32_t wi, uint32_t *ei) > > { > > - bool varway56 = dtlb ? > > - env->config->dtlb.varway56 : > > - env->config->itlb.varway56; > > - > > if (!dtlb) { > > wi &= 7; > > } > > @@ -195,7 +184,7 @@ static void split_tlb_entry_spec_way(const > > CPUXtensaState *env, uint32_t v, > > break; > > > > case 5: > > - if (varway56) { > > + if (env->config->tlb_variable_way[5]) { > > uint32_t eibase = 27 + get_page_size(env, dtlb, wi); > > *ei = (v >> eibase) & 0x3; > > } else { > > @@ -204,7 +193,7 @@ static void split_tlb_entry_spec_way(const > > CPUXtensaState *env, uint32_t v, > > break; > > > > case 6: > > - if (varway56) { > > + if (env->config->tlb_variable_way[6]) { > > uint32_t eibase = 29 - get_page_size(env, dtlb, wi); > > *ei = (v >> eibase) & 0x7; > > } else { > > There's no direct code duplication, but it definitely feels like > the logic for "figure out how many bits we're dealing with" is > duplicated across these three functions. > > I think it ought to be possible to have a function (or maybe two) > which take account of both the way number and tlb_get_variable_way[] > such that all of these three functions then don't need to have > a switch on the way or look at tlb_variable_way[] themselves... Ok, let me have another look at cleaning this up. -- Thanks. -- Max