RE: [PATCH v2 10/12] target/riscv: Add kvm_riscv_get/put_regs_timer
-----Original Message-----
From: Richard Henderson [mailto:richard.henderson@linaro.org]
Sent: Monday, December 13, 2021 11:20 PM
To: Anup Patel <anup(a)brainfault.org>; Jiangyifei <jiangyifei(a)huawei.com>
Cc: Bin Meng <bin.meng(a)windriver.com>; open list:RISC-V
<qemu-riscv(a)nongnu.org>; limingwang (A) <limingwang(a)huawei.com>; KVM
General <kvm(a)vger.kernel.org>; libvir-list(a)redhat.com; Anup Patel
<anup.patel(a)wdc.com>; QEMU Developers <qemu-devel(a)nongnu.org>;
wanbo (G) <wanbo13(a)huawei.com>; Palmer Dabbelt <palmer(a)dabbelt.com>;
kvm-riscv(a)lists.infradead.org; Wanghaibin (D)
<wanghaibin.wang(a)huawei.com>; Alistair Francis
<Alistair.Francis(a)wdc.com>; Fanliang (EulerOS) <fanliang(a)huawei.com>;
Wubin (H) <wu.wubin(a)huawei.com>
Subject: Re: [PATCH v2 10/12] target/riscv: Add kvm_riscv_get/put_regs_timer
On 12/12/21 9:05 PM, Anup Patel wrote:
>> + ret = kvm_get_one_reg(cs, RISCV_TIMER_REG(env, state), ®);
>> + if (ret) {
>> + abort();
>> + }
>> + env->kvm_timer_state = reg;
>
> Please read the timer frequency here.
Yep.
>> +
>> + env->kvm_timer_dirty = true;
>> +}
>> +
>> +static void kvm_riscv_put_regs_timer(CPUState *cs) {
>> + int ret;
>> + uint64_t reg;
>> + CPURISCVState *env = &RISCV_CPU(cs)->env;
>> +
>> + if (!env->kvm_timer_dirty) {
>> + return;
>> + }
>
> Over here, we should get the timer frequency and abort() with an error
> message if it does not match env->kvm_timer_frequency
>
> For now, migration will not work between Hosts with different timer
> frequency.
You shouldn't have to do this every "put", only on migration, at which
point you
can actually signal a migration error rather than aborting directly.
r~
Yes, it will be modified in the next series.
Yifei