On Fri, Dec 15, 2023 at 02:37:32PM +0530, Anup Patel wrote:
> On Thu, Dec 14, 2023 at 3:46 PM Andrew Jones <ajones@xxxxxxxxxxxxxxxx> wrote:
> >
> > KVM's implementation of SBI STA needs to track the address of each
> > VCPU's steal-time shared memory region as well as the amount of
> > stolen time. Add a structure to vcpu_arch to contain this state
> > and make sure that the address is always set to INVALID_GPA on
> > vcpu reset. And, of course, ensure KVM won't try to update steal-
> > time when the shared memory address is invalid.
> >
> > Signed-off-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>
> > ---
> > arch/riscv/include/asm/kvm_host.h | 6 ++++++
> > arch/riscv/kvm/vcpu.c | 2 ++
> > arch/riscv/kvm/vcpu_sbi_sta.c | 4 ++++
> > 3 files changed, 12 insertions(+)
> >
> > diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> > index 230b82c3118d..b10026fb6412 100644
> > --- a/arch/riscv/include/asm/kvm_host.h
> > +++ b/arch/riscv/include/asm/kvm_host.h
> > @@ -263,6 +263,12 @@ struct kvm_vcpu_arch {
> >
> > /* 'static' configurations which are set only once */
> > struct kvm_vcpu_config cfg;
> > +
> > + /* SBI steal-time accounting */
> > + struct {
> > + gpa_t shmem;
> > + u64 last_steal;
> > + } sta;
> > };
> >
> > static inline void kvm_arch_sync_events(struct kvm *kvm) {}
> > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> > index 6995b8b641e4..fec4f5fd0fa7 100644
> > --- a/arch/riscv/kvm/vcpu.c
> > +++ b/arch/riscv/kvm/vcpu.c
> > @@ -83,6 +83,8 @@ static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
> > vcpu->arch.hfence_tail = 0;
> > memset(vcpu->arch.hfence_queue, 0, sizeof(vcpu->arch.hfence_queue));
> >
> > + vcpu->arch.sta.shmem = INVALID_GPA;
> > +
>
> I think we should also set last_steal to zero as well.
>
> Also, let's add kvm_riscv_vcpu_sbi_sta_reset() in vcpu_sbi_sta.c
> to reset VCPU STA state.
Will do.
>
> > /* Reset the guest CSRs for hotplug usecase */
> > if (loaded)
> > kvm_arch_vcpu_load(vcpu, smp_processor_id());
> > diff --git a/arch/riscv/kvm/vcpu_sbi_sta.c b/arch/riscv/kvm/vcpu_sbi_sta.c
> > index e28351c9488b..157c199be0b4 100644
> > --- a/arch/riscv/kvm/vcpu_sbi_sta.c
> > +++ b/arch/riscv/kvm/vcpu_sbi_sta.c
> > @@ -10,6 +10,10 @@
> >
> > void kvm_riscv_vcpu_record_steal_time(struct kvm_vcpu *vcpu)
> > {
> > + gpa_t shmem = vcpu->arch.sta.shmem;
> > +
> > + if (shmem == INVALID_GPA)
> > + return;
> > }
> >
> > static int kvm_sbi_sta_steal_time_set_shmem(struct kvm_vcpu *vcpu)
> > --
> > 2.43.0
> >
>
> Apart from the above, it looks good to me.
>
> Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx>
Thanks,
drew
