Re: [PATCH v4 06/13] KVM: arm64: Add standard hypervisor firmware register

From: Raghavendra Rao Ananta <rananta@google.com>
To: Oliver Upton <oupton@google.com>
Cc: Marc Zyngier <maz@kernel.org>, Andrew Jones <drjones@redhat.com>,
	James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Peter Shier <pshier@google.com>,
	Ricardo Koller <ricarkol@google.com>,
	Reiji Watanabe <reijiw@google.com>,
	Jing Zhang <jingzhangos@google.com>,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org
Subject: Re: [PATCH v4 06/13] KVM: arm64: Add standard hypervisor firmware register
Date: Mon, 14 Mar 2022 17:23:27 -0700	[thread overview]
Message-ID: <CAJHc60yJQ4VOq9OoyGncL07bfvQuz0mPYXCVf2WhL-8QzM5-nA@mail.gmail.com> (raw)
In-Reply-To: <Yi+bVM742+9W4TYj@google.com>

On Mon, Mar 14, 2022 at 12:45 PM Oliver Upton <oupton@google.com> wrote:
>
> On Thu, Feb 24, 2022 at 05:25:52PM +0000, Raghavendra Rao Ananta wrote:
> > Introduce the firmware register to hold the standard hypervisor
> > service calls (owner value 5) as a bitmap. The bitmap represents
> > the features that'll be enabled for the guest, as configured by
> > the user-space. Currently, this includes support only for
> > Paravirtualized time, represented by bit-0.
> >
> > The register is also added to the kvm_arm_vm_scope_fw_regs[] list
> > as it maintains its state per-VM.
> >
> > Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
> > ---
> >  arch/arm64/include/asm/kvm_host.h |  2 ++
> >  arch/arm64/include/uapi/asm/kvm.h |  4 ++++
> >  arch/arm64/kvm/guest.c            |  1 +
> >  arch/arm64/kvm/hypercalls.c       | 20 +++++++++++++++++++-
> >  include/kvm/arm_hypercalls.h      |  3 +++
> >  5 files changed, 29 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> > index 1909ced3208f..318148b69279 100644
> > --- a/arch/arm64/include/asm/kvm_host.h
> > +++ b/arch/arm64/include/asm/kvm_host.h
> > @@ -105,9 +105,11 @@ struct kvm_arch_memory_slot {
> >   * struct kvm_hvc_desc: KVM ARM64 hypercall descriptor
> >   *
> >   * @hvc_std_bmap: Bitmap of standard secure service calls
> > + * @hvc_std_hyp_bmap: Bitmap of standard hypervisor service calls
> >   */
> >  struct kvm_hvc_desc {
> >       u64 hvc_std_bmap;
> > +     u64 hvc_std_hyp_bmap;
> >  };
> >
> >  struct kvm_arch {
> > diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
> > index 2decc30d6b84..9a2caead7359 100644
> > --- a/arch/arm64/include/uapi/asm/kvm.h
> > +++ b/arch/arm64/include/uapi/asm/kvm.h
> > @@ -295,6 +295,10 @@ struct kvm_arm_copy_mte_tags {
> >  #define KVM_REG_ARM_STD_BIT_TRNG_V1_0                BIT(0)
> >  #define KVM_REG_ARM_STD_BMAP_BIT_MAX         0       /* Last valid bit */
> >
> > +#define KVM_REG_ARM_STD_HYP_BMAP             KVM_REG_ARM_FW_BMAP_REG(1)
> > +#define KVM_REG_ARM_STD_HYP_BIT_PV_TIME              BIT(0)
> > +#define KVM_REG_ARM_STD_HYP_BMAP_BIT_MAX     0       /* Last valid bit */
> > +
> >  /* SVE registers */
> >  #define KVM_REG_ARM64_SVE            (0x15 << KVM_REG_ARM_COPROC_SHIFT)
> >
> > diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> > index d66e6c742bbe..c42426d6137e 100644
> > --- a/arch/arm64/kvm/guest.c
> > +++ b/arch/arm64/kvm/guest.c
> > @@ -66,6 +66,7 @@ static const u64 kvm_arm_vm_scope_fw_regs[] = {
> >       KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1,
> >       KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2,
> >       KVM_REG_ARM_STD_BMAP,
> > +     KVM_REG_ARM_STD_HYP_BMAP,
> >  };
> >
> >  /**
> > diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
> > index 48c126c3da72..ebc0cc26cf2e 100644
> > --- a/arch/arm64/kvm/hypercalls.c
> > +++ b/arch/arm64/kvm/hypercalls.c
> > @@ -75,6 +75,10 @@ static bool kvm_hvc_call_supported(struct kvm_vcpu *vcpu, u32 func_id)
> >       case ARM_SMCCC_TRNG_RND64:
> >               return kvm_arm_fw_reg_feat_enabled(hvc_desc->hvc_std_bmap,
> >                                               KVM_REG_ARM_STD_BIT_TRNG_V1_0);
> > +     case ARM_SMCCC_HV_PV_TIME_FEATURES:
> > +     case ARM_SMCCC_HV_PV_TIME_ST:
> > +             return kvm_arm_fw_reg_feat_enabled(hvc_desc->hvc_std_hyp_bmap,
> > +                                     KVM_REG_ARM_STD_HYP_BIT_PV_TIME);
> >       default:
> >               /* By default, allow the services that aren't listed here */
> >               return true;
> > @@ -83,6 +87,7 @@ static bool kvm_hvc_call_supported(struct kvm_vcpu *vcpu, u32 func_id)
> >
> >  int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
> >  {
> > +     struct kvm_hvc_desc *hvc_desc = &vcpu->kvm->arch.hvc_desc;
> >       u32 func_id = smccc_get_function(vcpu);
> >       u64 val[4] = {SMCCC_RET_NOT_SUPPORTED};
> >       u32 feature;
> > @@ -134,7 +139,10 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
> >                       }
> >                       break;
> >               case ARM_SMCCC_HV_PV_TIME_FEATURES:
> > -                     val[0] = SMCCC_RET_SUCCESS;
> > +                     if (kvm_arm_fw_reg_feat_enabled(
> > +                                     hvc_desc->hvc_std_hyp_bmap,
>
> It is probably OK to keep this parameter on the line above (just stay
> under 100 characters a line).
>
Will rearrange this in the next series. Thanks.

Regards,
Raghavendra
> > +                                     KVM_REG_ARM_STD_HYP_BIT_PV_TIME))
> > +                             val[0] = SMCCC_RET_SUCCESS;
> >                       break;
> >               }
> >               break;
> > @@ -179,6 +187,7 @@ static const u64 kvm_arm_fw_reg_ids[] = {
> >       KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1,
> >       KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2,
> >       KVM_REG_ARM_STD_BMAP,
> > +     KVM_REG_ARM_STD_HYP_BMAP,
> >  };
> >
> >  void kvm_arm_init_hypercalls(struct kvm *kvm)
> > @@ -186,6 +195,7 @@ void kvm_arm_init_hypercalls(struct kvm *kvm)
> >       struct kvm_hvc_desc *hvc_desc = &kvm->arch.hvc_desc;
> >
> >       hvc_desc->hvc_std_bmap = ARM_SMCCC_STD_FEATURES;
> > +     hvc_desc->hvc_std_hyp_bmap = ARM_SMCCC_STD_HYP_FEATURES;
> >  }
> >
> >  int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
> > @@ -272,6 +282,9 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> >       case KVM_REG_ARM_STD_BMAP:
> >               val = READ_ONCE(hvc_desc->hvc_std_bmap);
> >               break;
> > +     case KVM_REG_ARM_STD_HYP_BMAP:
> > +             val = READ_ONCE(hvc_desc->hvc_std_hyp_bmap);
> > +             break;
> >       default:
> >               return -ENOENT;
> >       }
> > @@ -294,6 +307,10 @@ static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
> >               fw_reg_bmap = &hvc_desc->hvc_std_bmap;
> >               fw_reg_features = ARM_SMCCC_STD_FEATURES;
> >               break;
> > +     case KVM_REG_ARM_STD_HYP_BMAP:
> > +             fw_reg_bmap = &hvc_desc->hvc_std_hyp_bmap;
> > +             fw_reg_features = ARM_SMCCC_STD_HYP_FEATURES;
> > +             break;
> >       default:
> >               return -ENOENT;
> >       }
> > @@ -398,6 +415,7 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> >
> >               return 0;
> >       case KVM_REG_ARM_STD_BMAP:
> > +     case KVM_REG_ARM_STD_HYP_BMAP:
> >               return kvm_arm_set_fw_reg_bmap(vcpu, reg_id, val);
> >       default:
> >               return -ENOENT;
> > diff --git a/include/kvm/arm_hypercalls.h b/include/kvm/arm_hypercalls.h
> > index 64d30b452809..a1cb6e839c74 100644
> > --- a/include/kvm/arm_hypercalls.h
> > +++ b/include/kvm/arm_hypercalls.h
> > @@ -9,6 +9,9 @@
> >  #define ARM_SMCCC_STD_FEATURES \
> >       GENMASK_ULL(KVM_REG_ARM_STD_BMAP_BIT_MAX, 0)
> >
> > +#define ARM_SMCCC_STD_HYP_FEATURES \
> > +     GENMASK_ULL(KVM_REG_ARM_STD_HYP_BMAP_BIT_MAX, 0)
> > +
> >  int kvm_hvc_call_handler(struct kvm_vcpu *vcpu);
> >
> >  static inline u32 smccc_get_function(struct kvm_vcpu *vcpu)
> > --
> > 2.35.1.473.g83b2b277ed-goog
> >