On Fri, May 12, 2023 at 10:42 PM Daniel Henrique Barboza <dbarb...@ventanamicro.com> wrote: > > Alistair, > > > Since this is the only patch that is being contested is it possible to apply > all > the other ones to riscv-to-apply.next? > > I'm asking because I'm going to send more code that will affect cpu_init() and > riscv_cpu_realize() functions, and it would be easier if the cleanups were > already > in 'next'. Otherwise I'll either have to base the new code on top of this > pending > series or I'll base them under riscv-to-apply.next and we'll have to deal with > conflicts.
Urgh, that's fair. I just replied to your other thread. Let's throw a guest error print in here and then we can merge it Alistair > > > Thanks, > > Daniel > > On 4/21/23 10:27, Daniel Henrique Barboza wrote: > > write_misa() must use as much common logic as possible. We want to open > > code just the bits that are exclusive to the CSR write operation and TCG > > internals. > > > > Our validation is done with riscv_cpu_validate_set_extensions(), but we > > need a small tweak first. When enabling RVG we're doing: > > > > env->misa_ext |= RVI | RVM | RVA | RVF | RVD; > > env->misa_ext_mask = env->misa_ext; > > > > This works fine for realize() time but this can potentially overwrite > > env->misa_ext_mask if we reutilize the function for write_misa(). > > > > Instead of doing misa_ext_mask = misa_ext, sum up the RVG extensions in > > misa_ext_mask as well. This won't change realize() time behavior > > (misa_ext_mask will be == misa_ext) and will ensure that write_misa() > > won't change misa_ext_mask by accident. > > > > After that, rewrite write_misa() to work as follows: > > > > - mask the write using misa_ext_mask to avoid enabling unsupported > > extensions; > > > > - suppress RVC if the next insn isn't aligned; > > > > - disable RVG if any of RVG dependencies are being disabled by the user; > > > > - assign env->misa_ext and run riscv_cpu_validate_set_extensions(). On > > error, rollback env->misa_ext to its original value; > > > > - handle RVF and MSTATUS_FS and continue as usual. > > > > Let's keep write_misa() as experimental for now until this logic gains > > enough mileage. > > > > Signed-off-by: Daniel Henrique Barboza <dbarb...@ventanamicro.com> > > Reviewed-by: Weiwei Li <liwei...@iscas.ac.cn> > > --- > > target/riscv/cpu.c | 4 ++-- > > target/riscv/cpu.h | 1 + > > target/riscv/csr.c | 47 ++++++++++++++++++++-------------------------- > > 3 files changed, 23 insertions(+), 29 deletions(-) > > > > diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c > > index 7d407321aa..4fa720a39d 100644 > > --- a/target/riscv/cpu.c > > +++ b/target/riscv/cpu.c > > @@ -944,7 +944,7 @@ static void riscv_cpu_validate_misa_mxl(RISCVCPU *cpu, > > Error **errp) > > * Check consistency between chosen extensions while setting > > * cpu->cfg accordingly. > > */ > > -static void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp) > > +void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp) > > { > > CPURISCVState *env = &cpu->env; > > Error *local_err = NULL; > > @@ -960,7 +960,7 @@ static void riscv_cpu_validate_set_extensions(RISCVCPU > > *cpu, Error **errp) > > cpu->cfg.ext_ifencei = true; > > > > env->misa_ext |= RVI | RVM | RVA | RVF | RVD; > > - env->misa_ext_mask = env->misa_ext; > > + env->misa_ext_mask |= RVI | RVM | RVA | RVF | RVD; > > } > > > > if (riscv_has_ext(env, RVI) && riscv_has_ext(env, RVE)) { > > diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h > > index 15423585d0..1f39edc687 100644 > > --- a/target/riscv/cpu.h > > +++ b/target/riscv/cpu.h > > @@ -548,6 +548,7 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, > > int size, > > bool probe, uintptr_t retaddr); > > char *riscv_isa_string(RISCVCPU *cpu); > > void riscv_cpu_list(void); > > +void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp); > > > > #define cpu_list riscv_cpu_list > > #define cpu_mmu_index riscv_cpu_mmu_index > > diff --git a/target/riscv/csr.c b/target/riscv/csr.c > > index 4451bd1263..4a3c57ea6f 100644 > > --- a/target/riscv/csr.c > > +++ b/target/riscv/csr.c > > @@ -1387,39 +1387,18 @@ static RISCVException read_misa(CPURISCVState *env, > > int csrno, > > static RISCVException write_misa(CPURISCVState *env, int csrno, > > target_ulong val) > > { > > + RISCVCPU *cpu = env_archcpu(env); > > + uint32_t orig_misa_ext = env->misa_ext; > > + Error *local_err = NULL; > > + > > if (!riscv_cpu_cfg(env)->misa_w) { > > /* drop write to misa */ > > return RISCV_EXCP_NONE; > > } > > > > - /* 'I' or 'E' must be present */ > > - if (!(val & (RVI | RVE))) { > > - /* It is not, drop write to misa */ > > - return RISCV_EXCP_NONE; > > - } > > - > > - /* 'E' excludes all other extensions */ > > - if (val & RVE) { > > - /* > > - * when we support 'E' we can do "val = RVE;" however > > - * for now we just drop writes if 'E' is present. > > - */ > > - return RISCV_EXCP_NONE; > > - } > > - > > - /* > > - * misa.MXL writes are not supported by QEMU. > > - * Drop writes to those bits. > > - */ > > - > > /* Mask extensions that are not supported by this hart */ > > val &= env->misa_ext_mask; > > > > - /* 'D' depends on 'F', so clear 'D' if 'F' is not present */ > > - if ((val & RVD) && !(val & RVF)) { > > - val &= ~RVD; > > - } > > - > > /* > > * Suppress 'C' if next instruction is not aligned > > * TODO: this should check next_pc > > @@ -1428,18 +1407,32 @@ static RISCVException write_misa(CPURISCVState > > *env, int csrno, > > val &= ~RVC; > > } > > > > + /* Disable RVG if any of its dependencies are disabled */ > > + if (!(val & RVI && val & RVM && val & RVA && > > + val & RVF && val & RVD)) { > > + val &= ~RVG; > > + } > > + > > /* If nothing changed, do nothing. */ > > if (val == env->misa_ext) { > > return RISCV_EXCP_NONE; > > } > > > > - if (!(val & RVF)) { > > + env->misa_ext = val; > > + riscv_cpu_validate_set_extensions(cpu, &local_err); > > + if (local_err != NULL) { > > + /* Rollback on validation error */ > > + env->misa_ext = orig_misa_ext; > > + > > + return RISCV_EXCP_NONE; > > + } > > + > > + if (!(env->misa_ext & RVF)) { > > env->mstatus &= ~MSTATUS_FS; > > } > > > > /* flush translation cache */ > > tb_flush(env_cpu(env)); > > - env->misa_ext = val; > > env->xl = riscv_cpu_mxl(env); > > return RISCV_EXCP_NONE; > > } >