| Message ID | 1524699938-6764-29-git-send-email-mjc@sifive.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Apr 25, 2018 at 5:14 PM Michael Clark <mjc@sifive.com> wrote: > Use the new CSR read/modify/write interface to implement > atomic updates to mip/sip. > Cc: Sagar Karandikar <sagark@eecs.berkeley.edu> > Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de> > Cc: Palmer Dabbelt <palmer@sifive.com> > Cc: Alistair Francis <Alistair.Francis@wdc.com> > Signed-off-by: Michael Clark <mjc@sifive.com> Reviewed-by: Alistair Francis <alistair.francis@wdc.com> Alistair > --- > target/riscv/csr.c | 56 +++++++++++++++++++++++++++--------------------------- > 1 file changed, 28 insertions(+), 28 deletions(-) > diff --git a/target/riscv/csr.c b/target/riscv/csr.c > index a424867..c704545 100644 > --- a/target/riscv/csr.c > +++ b/target/riscv/csr.c > @@ -491,25 +491,31 @@ static int write_mbadaddr(CPURISCVState *env, int csrno, target_ulong val) > return 0; > } > -static int read_mip(CPURISCVState *env, int csrno, target_ulong *val) > -{ > - *val = atomic_read(&env->mip); > - return 0; > -} > - > -static int write_mip(CPURISCVState *env, int csrno, target_ulong val) > +static int rmw_mip(CPURISCVState *env, int csrno, target_ulong *ret_value, > + target_ulong new_value, target_ulong write_mask) > { > RISCVCPU *cpu = riscv_env_get_cpu(env); > + target_ulong mask = write_mask & delegable_ints; > + uint32_t old_mip; > + > + /* We can't allow the supervisor to control SEIP as this would allow the > + * supervisor to clear a pending external interrupt which will result in > + * lost a interrupt in the case a PLIC is attached. The SEIP bit must be > + * hardware controlled when a PLIC is attached. This should be an option > + * for CPUs with software-delegated Supervisor External Interrupts. */ > + mask &= ~MIP_SEIP; > + > + if (mask) { > + qemu_mutex_lock_iothread(); > + old_mip = riscv_cpu_update_mip(cpu, mask, (new_value & mask)); > + qemu_mutex_unlock_iothread(); > + } else { > + old_mip = atomic_read(&env->mip); > + } > - /* > - * csrs, csrc on mip.SEIP is not decomposable into separate read and > - * write steps, so a different implementation is needed > - */ > - > - qemu_mutex_lock_iothread(); > - riscv_cpu_update_mip(cpu, MIP_SSIP | MIP_STIP, > - (val & (MIP_SSIP | MIP_STIP))); > - qemu_mutex_unlock_iothread(); > + if (ret_value) { > + *ret_value = old_mip; > + } > return 0; > } > @@ -627,17 +633,11 @@ static int write_sbadaddr(CPURISCVState *env, int csrno, target_ulong val) > return 0; > } > -static int read_sip(CPURISCVState *env, int csrno, target_ulong *val) > -{ > - *val = atomic_read(&env->mip) & env->mideleg; > - return 0; > -} > - > -static int write_sip(CPURISCVState *env, int csrno, target_ulong val) > +static int rmw_sip(CPURISCVState *env, int csrno, target_ulong *ret_value, > + target_ulong new_value, target_ulong write_mask) > { > - target_ulong newval = (atomic_read(&env->mip) & ~env->mideleg) > - | (val & env->mideleg); > - return write_mip(env, CSR_MIP, newval); > + return rmw_mip(env, CSR_MSTATUS, ret_value, new_value, > + write_mask & env->mideleg); > } > /* Supervisor Protection and Translation */ > @@ -819,7 +819,7 @@ static const riscv_csr_operations csr_ops[0xfff] = { > [CSR_MEPC] = { read_mepc, write_mepc }, > [CSR_MCAUSE] = { read_mcause, write_mcause }, > [CSR_MBADADDR] = { read_mbadaddr, write_mbadaddr }, > - [CSR_MIP] = { read_mip, write_mip }, > + [CSR_MIP] = { NULL, NULL, rmw_mip }, > /* Supervisor Trap Setup */ > [CSR_SSTATUS] = { read_sstatus, write_sstatus }, > @@ -832,7 +832,7 @@ static const riscv_csr_operations csr_ops[0xfff] = { > [CSR_SEPC] = { read_sepc, write_sepc }, > [CSR_SCAUSE] = { read_scause, write_scause }, > [CSR_SBADADDR] = { read_sbadaddr, write_sbadaddr }, > - [CSR_SIP] = { read_sip, write_sip }, > + [CSR_SIP] = { NULL, NULL, rmw_sip }, > /* Supervisor Protection and Translation */ > [CSR_SATP] = { read_satp, write_satp }, > -- > 2.7.0
diff --git a/target/riscv/csr.c b/target/riscv/csr.c index a424867..c704545 100644 --- a/target/riscv/csr.c +++ b/target/riscv/csr.c @@ -491,25 +491,31 @@ static int write_mbadaddr(CPURISCVState *env, int csrno, target_ulong val) return 0; } -static int read_mip(CPURISCVState *env, int csrno, target_ulong *val) -{ - *val = atomic_read(&env->mip); - return 0; -} - -static int write_mip(CPURISCVState *env, int csrno, target_ulong val) +static int rmw_mip(CPURISCVState *env, int csrno, target_ulong *ret_value, + target_ulong new_value, target_ulong write_mask) { RISCVCPU *cpu = riscv_env_get_cpu(env); + target_ulong mask = write_mask & delegable_ints; + uint32_t old_mip; + + /* We can't allow the supervisor to control SEIP as this would allow the + * supervisor to clear a pending external interrupt which will result in + * lost a interrupt in the case a PLIC is attached. The SEIP bit must be + * hardware controlled when a PLIC is attached. This should be an option + * for CPUs with software-delegated Supervisor External Interrupts. */ + mask &= ~MIP_SEIP; + + if (mask) { + qemu_mutex_lock_iothread(); + old_mip = riscv_cpu_update_mip(cpu, mask, (new_value & mask)); + qemu_mutex_unlock_iothread(); + } else { + old_mip = atomic_read(&env->mip); + } - /* - * csrs, csrc on mip.SEIP is not decomposable into separate read and - * write steps, so a different implementation is needed - */ - - qemu_mutex_lock_iothread(); - riscv_cpu_update_mip(cpu, MIP_SSIP | MIP_STIP, - (val & (MIP_SSIP | MIP_STIP))); - qemu_mutex_unlock_iothread(); + if (ret_value) { + *ret_value = old_mip; + } return 0; } @@ -627,17 +633,11 @@ static int write_sbadaddr(CPURISCVState *env, int csrno, target_ulong val) return 0; } -static int read_sip(CPURISCVState *env, int csrno, target_ulong *val) -{ - *val = atomic_read(&env->mip) & env->mideleg; - return 0; -} - -static int write_sip(CPURISCVState *env, int csrno, target_ulong val) +static int rmw_sip(CPURISCVState *env, int csrno, target_ulong *ret_value, + target_ulong new_value, target_ulong write_mask) { - target_ulong newval = (atomic_read(&env->mip) & ~env->mideleg) - | (val & env->mideleg); - return write_mip(env, CSR_MIP, newval); + return rmw_mip(env, CSR_MSTATUS, ret_value, new_value, + write_mask & env->mideleg); } /* Supervisor Protection and Translation */ @@ -819,7 +819,7 @@ static const riscv_csr_operations csr_ops[0xfff] = { [CSR_MEPC] = { read_mepc, write_mepc }, [CSR_MCAUSE] = { read_mcause, write_mcause }, [CSR_MBADADDR] = { read_mbadaddr, write_mbadaddr }, - [CSR_MIP] = { read_mip, write_mip }, + [CSR_MIP] = { NULL, NULL, rmw_mip }, /* Supervisor Trap Setup */ [CSR_SSTATUS] = { read_sstatus, write_sstatus }, @@ -832,7 +832,7 @@ static const riscv_csr_operations csr_ops[0xfff] = { [CSR_SEPC] = { read_sepc, write_sepc }, [CSR_SCAUSE] = { read_scause, write_scause }, [CSR_SBADADDR] = { read_sbadaddr, write_sbadaddr }, - [CSR_SIP] = { read_sip, write_sip }, + [CSR_SIP] = { NULL, NULL, rmw_sip }, /* Supervisor Protection and Translation */ [CSR_SATP] = { read_satp, write_satp },
Use the new CSR read/modify/write interface to implement atomic updates to mip/sip. Cc: Sagar Karandikar <sagark@eecs.berkeley.edu> Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de> Cc: Palmer Dabbelt <palmer@sifive.com> Cc: Alistair Francis <Alistair.Francis@wdc.com> Signed-off-by: Michael Clark <mjc@sifive.com> --- target/riscv/csr.c | 56 +++++++++++++++++++++++++++--------------------------- 1 file changed, 28 insertions(+), 28 deletions(-)