| Message ID | 20250218230936.408429-1-cyrilbur@tenstorrent.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [kvmtool,v3] riscv: Use the count parameter of term_putc in SBI_EXT_DBCN_CONSOLE_WRITE | expand |
On Tue, 18 Feb 2025 at 15:09, Cyril Bur <cyrilbur@tenstorrent.com> wrote: > > Currently each character of a string is term_putc()ed individually. This > causes a round trip into opensbi for each char. Very inefficient > especially since the interface term_putc() does accept a count. > > This patch passes a count to term_putc() in the > SBI_EXT_DBCN_CONSOLE_WRITE path. > > Signed-off-by: Cyril Bur <cyrilbur@tenstorrent.com> Reviewed-by: Joel Stanley <joel@jms.id.au> I added Will to cc so he can take a look and apply this for you. > --- > riscv/kvm-cpu.c | 22 ++++++++++++---------- > 1 file changed, 12 insertions(+), 10 deletions(-) > > diff --git a/riscv/kvm-cpu.c b/riscv/kvm-cpu.c > index 0c171da..84d35f7 100644 > --- a/riscv/kvm-cpu.c > +++ b/riscv/kvm-cpu.c > @@ -172,21 +172,23 @@ static bool kvm_cpu_riscv_sbi(struct kvm_cpu *vcpu) > str_start = guest_flat_to_host(vcpu->kvm, addr); > addr += vcpu->kvm_run->riscv_sbi.args[0] - 1; > str_end = guest_flat_to_host(vcpu->kvm, addr); > - if (!str_start || !str_end) { > + if (!str_start || !str_end || str_start > str_end) { > vcpu->kvm_run->riscv_sbi.ret[0] = > SBI_ERR_INVALID_PARAM; > break; > } > + if (vcpu->kvm_run->riscv_sbi.function_id == > + SBI_EXT_DBCN_CONSOLE_WRITE) { > + int length = (str_end - str_start) + 1; > + > + length = term_putc(str_start, length, 0); > + vcpu->kvm_run->riscv_sbi.ret[1] = length; > + break; > + } > + /* This will be SBI_EXT_DBCN_CONSOLE_READ */ > vcpu->kvm_run->riscv_sbi.ret[1] = 0; > - while (str_start <= str_end) { > - if (vcpu->kvm_run->riscv_sbi.function_id == > - SBI_EXT_DBCN_CONSOLE_WRITE) { > - term_putc(str_start, 1, 0); > - } else { > - if (!term_readable(0)) > - break; > - *str_start = term_getc(vcpu->kvm, 0); > - } > + while (str_start <= str_end && term_readable(0)) { > + *str_start = term_getc(vcpu->kvm, 0); > vcpu->kvm_run->riscv_sbi.ret[1]++; > str_start++; > } > -- > 2.34.1 >
diff --git a/riscv/kvm-cpu.c b/riscv/kvm-cpu.c index 0c171da..84d35f7 100644 --- a/riscv/kvm-cpu.c +++ b/riscv/kvm-cpu.c @@ -172,21 +172,23 @@ static bool kvm_cpu_riscv_sbi(struct kvm_cpu *vcpu) str_start = guest_flat_to_host(vcpu->kvm, addr); addr += vcpu->kvm_run->riscv_sbi.args[0] - 1; str_end = guest_flat_to_host(vcpu->kvm, addr); - if (!str_start || !str_end) { + if (!str_start || !str_end || str_start > str_end) { vcpu->kvm_run->riscv_sbi.ret[0] = SBI_ERR_INVALID_PARAM; break; } + if (vcpu->kvm_run->riscv_sbi.function_id == + SBI_EXT_DBCN_CONSOLE_WRITE) { + int length = (str_end - str_start) + 1; + + length = term_putc(str_start, length, 0); + vcpu->kvm_run->riscv_sbi.ret[1] = length; + break; + } + /* This will be SBI_EXT_DBCN_CONSOLE_READ */ vcpu->kvm_run->riscv_sbi.ret[1] = 0; - while (str_start <= str_end) { - if (vcpu->kvm_run->riscv_sbi.function_id == - SBI_EXT_DBCN_CONSOLE_WRITE) { - term_putc(str_start, 1, 0); - } else { - if (!term_readable(0)) - break; - *str_start = term_getc(vcpu->kvm, 0); - } + while (str_start <= str_end && term_readable(0)) { + *str_start = term_getc(vcpu->kvm, 0); vcpu->kvm_run->riscv_sbi.ret[1]++; str_start++; }
Currently each character of a string is term_putc()ed individually. This causes a round trip into opensbi for each char. Very inefficient especially since the interface term_putc() does accept a count. This patch passes a count to term_putc() in the SBI_EXT_DBCN_CONSOLE_WRITE path. Signed-off-by: Cyril Bur <cyrilbur@tenstorrent.com> --- riscv/kvm-cpu.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-)