2022-02-24 17:54:34

by Raghavendra Rao Ananta

Subject: [PATCH v4 04/13] KVM: arm64: Capture VM's first run

Capture the first run of the KVM VM, which is basically the
first KVM_RUN issued for any vCPU. This state of the VM is
helpful in the upcoming patches to prevent user-space from
configuring certain VM features, such as the feature bitmap
exposed by the psuedo-firmware registers, after the VM has
started running.

Signed-off-by: Raghavendra Rao Ananta <[email protected]>
---
arch/arm64/include/asm/kvm_host.h | 9 +++++++++
arch/arm64/kvm/arm.c | 2 ++
2 files changed, 11 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 657733554d98..e823571e50cc 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -139,6 +139,9 @@ struct kvm_arch {

/* Register scoping enabled for KVM registers */
bool reg_scope_enabled;
+
+ /* Capture first run of the VM */
+ bool has_run_once;
};

struct kvm_vcpu_fault_info {
@@ -796,6 +799,12 @@ bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu);
int kvm_trng_call(struct kvm_vcpu *vcpu);
int kvm_arm_reg_id_encode_scope(struct kvm_vcpu *vcpu, u64 *reg_id);
void kvm_arm_reg_id_clear_scope(struct kvm_vcpu *vcpu, u64 *reg_id);
+
+static inline bool kvm_arm_vm_has_run_once(struct kvm_arch *kvm_arch)
+{
+ return kvm_arch->has_run_once;
+}
+
#ifdef CONFIG_KVM
extern phys_addr_t hyp_mem_base;
extern phys_addr_t hyp_mem_size;
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 107977c82c6c..f61cd8d57eae 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -635,6 +635,8 @@ int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu)
if (kvm_vm_is_protected(kvm))
kvm_call_hyp_nvhe(__pkvm_vcpu_init_traps, vcpu);

+ kvm->arch.has_run_once = true;
+
return ret;
}

--
2.35.1.473.g83b2b277ed-goog

2022-03-15 05:37:35

by Oliver Upton

Subject: Re: [PATCH v4 04/13] KVM: arm64: Capture VM's first run

Hi Raghavendra,

On Thu, Feb 24, 2022 at 05:25:50PM +0000, Raghavendra Rao Ananta wrote:
> Capture the first run of the KVM VM, which is basically the
> first KVM_RUN issued for any vCPU. This state of the VM is
> helpful in the upcoming patches to prevent user-space from
> configuring certain VM features, such as the feature bitmap
> exposed by the psuedo-firmware registers, after the VM has
> started running.
>
> Signed-off-by: Raghavendra Rao Ananta <[email protected]>

I believe this patch is superseded by commit:

5177fe91e4cf ("KVM: arm64: Do not change the PMU event filter after a VCPU has run")

on kvmarm/next.

--
Thanks,
Oliver

2022-03-17 05:36:24

by Raghavendra Rao Ananta

Subject: Re: [PATCH v4 04/13] KVM: arm64: Capture VM's first run

On Mon, Mar 14, 2022 at 11:02 AM Oliver Upton <[email protected]> wrote:
Hi Oliver,
>
> Hi Raghavendra,
>
> On Thu, Feb 24, 2022 at 05:25:50PM +0000, Raghavendra Rao Ananta wrote:
> > Capture the first run of the KVM VM, which is basically the
> > first KVM_RUN issued for any vCPU. This state of the VM is
> > helpful in the upcoming patches to prevent user-space from
> > configuring certain VM features, such as the feature bitmap
> > exposed by the psuedo-firmware registers, after the VM has
> > started running.
> >
> > Signed-off-by: Raghavendra Rao Ananta <[email protected]>
>
> I believe this patch is superseded by commit:
>
> 5177fe91e4cf ("KVM: arm64: Do not change the PMU event filter after a VCPU has run")
>
> on kvmarm/next.
>
Perfect! Just what we needed. I'll drop this patch.

Regards,
Raghavendra
>
> --
> Thanks,
> Oliver