Re: [PATCH] LoongArch: KVM: Reload guest CSR registers after S4

[bibo mao]

On 2025/3/3 下午10:06, Huacai Chen wrote:
> Hi, Bibo,
>
> On Mon, Mar 3, 2025 at 5:11 PM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:
> > On host HW guest CSR registers are lost after suspend and resume
> > operation. Since last_vcpu of boot CPU still records latest vCPU pointer
> > so that guest CSR register skips to reload when boot CPU resumes and
> > vCPU is scheduled.
> >
> > Here last_vcpu is cleared so that guest CSR register will reload from
> > scheduled vCPU context after suspend and resume.
> >
> > Also there is another small fix for Loongson AVEC support, bit 14 is added
> > in CSR ESTAT register. Macro CSR_ESTAT_IS is replaced with hardcoded value
> > 0x1fff and AVEC interrupt status bit 14 is supported with macro
> > CSR_ESTAT_IS.
> >
> > Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
> > ---
> >   arch/loongarch/kvm/main.c | 8 ++++++++
> >   arch/loongarch/kvm/vcpu.c | 2 +-
> >   2 files changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/loongarch/kvm/main.c b/arch/loongarch/kvm/main.c
> > index f6d3242b9234..b177773f38f6 100644
> > --- a/arch/loongarch/kvm/main.c
> > +++ b/arch/loongarch/kvm/main.c
> > @@ -284,6 +284,7 @@ long kvm_arch_dev_ioctl(struct file *filp,
> >   int kvm_arch_enable_virtualization_cpu(void)
> >   {
> >          unsigned long env, gcfg = 0;
> > +       struct kvm_context *context;
> >
> >          env = read_csr_gcfg();
> >
> > @@ -317,6 +318,13 @@ int kvm_arch_enable_virtualization_cpu(void)
> >          kvm_debug("GCFG:%lx GSTAT:%lx GINTC:%lx GTLBC:%lx",
> >                    read_csr_gcfg(), read_csr_gstat(), read_csr_gintc(), read_csr_gtlbc());
> >
> > +       /*
> > +        * HW Guest CSR registers are lost after CPU suspend and resume
> > +        * Clear last_vcpu so that Guest CSR register forced to reload
> > +        * from vCPU SW state
> > +        */
> > +       context = this_cpu_ptr(vmcs);
> > +       context->last_vcpu = NULL;
> This can be simplified as this_cpu_ptr(vmcs)->last_vcpu = NULL;
Sure, will do.
> >          return 0;
> >   }
> >
> > diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
> > index 20f941af3e9e..9e1a9b4aa4c6 100644
> > --- a/arch/loongarch/kvm/vcpu.c
> > +++ b/arch/loongarch/kvm/vcpu.c
> > @@ -311,7 +311,7 @@ static int kvm_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
> >   {
> >          int ret = RESUME_GUEST;
> >          unsigned long estat = vcpu->arch.host_estat;
> > -       u32 intr = estat & 0x1fff; /* Ignore NMI */
> > +       u32 intr = estat & CSR_ESTAT_IS;
> This part has nothing to do with S4, please split to another patch.
ok, will split into two patches.

Regards
Bibo Mao
> Huacai
>
> >          u32 ecode = (estat & CSR_ESTAT_EXC) >> CSR_ESTAT_EXC_SHIFT;
> >
> >          vcpu->mode = OUTSIDE_GUEST_MODE;
> >
> > base-commit: 1e15510b71c99c6e49134d756df91069f7d18141
> > --
> > 2.39.3