Subject: [PATCH v2 7/7] ARM: KVM: Unlock vgic-v3 support

From: [email-masked] (Christoffer Dall)
Date: Mon, 5 Sep 2016 13:29:27 +0200

On Tue, Aug 16, 2016 at 11:46:58AM +0100, Vladimir Murzin wrote:
> It is time to get access to common version of vgic-v3.

common version?

> 
> We basically would need to tell build system how to pick it up and
> undo KVM_ARM_VGIC_V3 guarding introduced in 4f64cb6 ("arm/arm64: KVM:
> Only allow 64bit hosts to build VGICv3") and remove stubs. However,
> since vgic got ITS support KVM_ARM_VGIC_V3 tend to protect a little
> bit more than just plain vgic-v3 - this guard is used for ITS too
> which is not supported in 32-bit world yet.  So, along with removal of
> KVM_ARM_VGIC_V3 guard introduce the new one - KVM_ARM_VGIC_V3_ITS to
> protect ITS related code.

I don't find this paragraph particularly helpful, I'm afraid.

> 
> The only unpleasant part is how we decide which save/restore sequence to
> use under __vgic_save_state() - we don't have patching framework in hand
> like arm64, so have to check runtime on every invocation.

Do static keys work on 32-bit arm?

> 
> Signed-off-by: Vladimir Murzin <[email-masked]>
> ---
>  arch/arm/include/asm/kvm_host.h     |    4 +++
>  arch/arm/include/asm/kvm_hyp.h      |    5 ++++
>  arch/arm/kvm/Makefile               |    2 ++
>  arch/arm/kvm/hyp/Makefile           |    1 +
>  arch/arm/kvm/hyp/switch.c           |   20 +++++++++++--
>  arch/arm64/kvm/Kconfig              |    4 +--
>  include/kvm/arm_vgic.h              |    8 ------
>  virt/kvm/arm/vgic/vgic-kvm-device.c |   10 ++-----
>  virt/kvm/arm/vgic/vgic-mmio-v3.c    |    2 ++
>  virt/kvm/arm/vgic/vgic-mmio.c       |    2 --
>  virt/kvm/arm/vgic/vgic-mmio.h       |    3 --
>  virt/kvm/arm/vgic/vgic.h            |   54 ++---------------------------------
>  12 files changed, 38 insertions(+), 77 deletions(-)
> 
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index de338d9..1312597 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -39,7 +39,11 @@
>  
>  #include <kvm/arm_vgic.h>
>  
> +#ifdef CONFIG_ARM_GIC_V3
> +#define KVM_MAX_VCPUS VGIC_V3_MAX_CPUS
> +#else
>  #define KVM_MAX_VCPUS VGIC_V2_MAX_CPUS
> +#endif
>  
>  #define KVM_REQ_VCPU_EXIT	8
>  
> diff --git a/arch/arm/include/asm/kvm_hyp.h b/arch/arm/include/asm/kvm_hyp.h
> index e604ad68..95669b3 100644
> --- a/arch/arm/include/asm/kvm_hyp.h
> +++ b/arch/arm/include/asm/kvm_hyp.h
> @@ -88,6 +88,8 @@
>  
>  #define VFP_FPEXC	__ACCESS_VFP(FPEXC)
>  
> +#define ID_PFR1		__ACCESS_CP15(c0, 0, c1, 1)
> +
>  /* AArch64 compatibility macros, only for the timer so far */
>  #define read_sysreg_el0(r)		read_sysreg(r##_el0)
>  #define write_sysreg_el0(v, r)		write_sysreg(v, r##_el0)
> @@ -103,6 +105,9 @@ void __timer_restore_state(struct kvm_vcpu *vcpu);
>  void __vgic_v2_save_state(struct kvm_vcpu *vcpu);
>  void __vgic_v2_restore_state(struct kvm_vcpu *vcpu);
>  
> +void __vgic_v3_save_state(struct kvm_vcpu *vcpu);
> +void __vgic_v3_restore_state(struct kvm_vcpu *vcpu);
> +
>  void __sysreg_save_state(struct kvm_cpu_context *ctxt);
>  void __sysreg_restore_state(struct kvm_cpu_context *ctxt);
>  
> diff --git a/arch/arm/kvm/Makefile b/arch/arm/kvm/Makefile
> index 10d77a6..043d817f 100644
> --- a/arch/arm/kvm/Makefile
> +++ b/arch/arm/kvm/Makefile
> @@ -26,8 +26,10 @@ obj-y += $(KVM)/arm/vgic/vgic.o
>  obj-y += $(KVM)/arm/vgic/vgic-init.o
>  obj-y += $(KVM)/arm/vgic/vgic-irqfd.o
>  obj-y += $(KVM)/arm/vgic/vgic-v2.o
> +obj-y += $(KVM)/arm/vgic/vgic-v3.o
>  obj-y += $(KVM)/arm/vgic/vgic-mmio.o
>  obj-y += $(KVM)/arm/vgic/vgic-mmio-v2.o
> +obj-y += $(KVM)/arm/vgic/vgic-mmio-v3.o
>  obj-y += $(KVM)/arm/vgic/vgic-kvm-device.o
>  obj-y += $(KVM)/irqchip.o
>  obj-y += $(KVM)/arm/arch_timer.o
> diff --git a/arch/arm/kvm/hyp/Makefile b/arch/arm/kvm/hyp/Makefile
> index 8dfa5f7..3023bb5 100644
> --- a/arch/arm/kvm/hyp/Makefile
> +++ b/arch/arm/kvm/hyp/Makefile
> @@ -5,6 +5,7 @@
>  KVM=../../../../virt/kvm
>  
>  obj-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/hyp/vgic-v2-sr.o
> +obj-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/hyp/vgic-v3-sr.o
>  obj-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/hyp/timer-sr.o
>  
>  obj-$(CONFIG_KVM_ARM_HOST) += tlb.o
> diff --git a/arch/arm/kvm/hyp/switch.c b/arch/arm/kvm/hyp/switch.c
> index b13caa9..9666bae 100644
> --- a/arch/arm/kvm/hyp/switch.c
> +++ b/arch/arm/kvm/hyp/switch.c
> @@ -15,6 +15,8 @@
>   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>   */
>  
> +#include <linux/irqchip/arm-gic-v3.h>
> +
>  #include <asm/kvm_asm.h>
>  #include <asm/kvm_hyp.h>
>  
> @@ -74,14 +76,28 @@ static void __hyp_text __deactivate_vm(struct kvm_vcpu *vcpu)
>  	write_sysreg(read_sysreg(MIDR), VPIDR);
>  }
>  
> +static bool __hyp_text __has_useable_gicv3_cpuif(void)
> +{
> +	if (IS_ENABLED(CONFIG_ARM_GIC_V3) && (read_sysreg(ID_PFR1) >> 28))

Do we have a define for bit 28 we could use?

Does this actually work on all v7 boards?  The v7 ARM ARM seems to state
that this bitfield is Reserved, UNK.  Does that somehow mean 'is going
to be zero'?

> +		return !!(read_sysreg(ICC_HSRE) & ICC_SRE_EL2_SRE);
> +	else
> +		return false;
> +}
> +
>  static void __hyp_text __vgic_save_state(struct kvm_vcpu *vcpu)
>  {
> -	__vgic_v2_save_state(vcpu);
> +	if (__has_useable_gicv3_cpuif())
> +		__vgic_v3_save_state(vcpu);
> +	else
> +		__vgic_v2_save_state(vcpu);
>  }
>  
>  static void __hyp_text __vgic_restore_state(struct kvm_vcpu *vcpu)
>  {
> -	__vgic_v2_restore_state(vcpu);
> +	if (__has_useable_gicv3_cpuif())
> +		__vgic_v3_restore_state(vcpu);
> +	else
> +		__vgic_v2_restore_state(vcpu);
>  }
>  
>  static bool __hyp_text __populate_fault_info(struct kvm_vcpu *vcpu)
> diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
> index 9c9edc9..6eaf12c 100644
> --- a/arch/arm64/kvm/Kconfig
> +++ b/arch/arm64/kvm/Kconfig
> @@ -16,7 +16,7 @@ menuconfig VIRTUALIZATION
>  
>  if VIRTUALIZATION
>  
> -config KVM_ARM_VGIC_V3
> +config KVM_ARM_VGIC_V3_ITS

I feel like this could have been simplified with adding the new ITS
guard in a separate patch.

In fact, you could then have a separate patch that enables compilation
of the gicv3 code and removes the static inlines etc., and then finally
a patch that adds in the logic for the world switch.

>  	bool
>  
>  config KVM
> @@ -34,7 +34,7 @@ config KVM
>  	select KVM_VFIO
>  	select HAVE_KVM_EVENTFD
>  	select HAVE_KVM_IRQFD
> -	select KVM_ARM_VGIC_V3
> +	select KVM_ARM_VGIC_V3_ITS
>  	select KVM_ARM_PMU if HW_PERF_EVENTS
>  	select HAVE_KVM_MSI
>  	select HAVE_KVM_IRQCHIP
> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
> index 19b698e..7462138 100644
> --- a/include/kvm/arm_vgic.h
> +++ b/include/kvm/arm_vgic.h
> @@ -217,7 +217,6 @@ struct vgic_v2_cpu_if {
>  };
>  
>  struct vgic_v3_cpu_if {
> -#ifdef CONFIG_KVM_ARM_VGIC_V3
>  	u32		vgic_hcr;
>  	u32		vgic_vmcr;
>  	u32		vgic_sre;	/* Restored only, change ignored */
> @@ -227,7 +226,6 @@ struct vgic_v3_cpu_if {
>  	u32		vgic_ap0r[4];
>  	u32		vgic_ap1r[4];
>  	u64		vgic_lr[VGIC_V3_MAX_LRS];
> -#endif
>  };
>  
>  struct vgic_cpu {
> @@ -294,13 +292,7 @@ bool kvm_vcpu_has_pending_irqs(struct kvm_vcpu *vcpu);
>  void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu);
>  void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu);
>  
> -#ifdef CONFIG_KVM_ARM_VGIC_V3
>  void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg);
> -#else
> -static inline void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg)
> -{
> -}
> -#endif
>  
>  /**
>   * kvm_vgic_get_max_vcpus - Get the maximum number of VCPUs allowed by HW
> diff --git a/virt/kvm/arm/vgic/vgic-kvm-device.c b/virt/kvm/arm/vgic/vgic-kvm-device.c
> index 1813f93..e4f0c33 100644
> --- a/virt/kvm/arm/vgic/vgic-kvm-device.c
> +++ b/virt/kvm/arm/vgic/vgic-kvm-device.c
> @@ -71,7 +71,6 @@ int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool write)
>  		addr_ptr = &vgic->vgic_cpu_base;
>  		alignment = SZ_4K;
>  		break;
> -#ifdef CONFIG_KVM_ARM_VGIC_V3
>  	case KVM_VGIC_V3_ADDR_TYPE_DIST:
>  		type_needed = KVM_DEV_TYPE_ARM_VGIC_V3;
>  		addr_ptr = &vgic->vgic_dist_base;
> @@ -82,7 +81,6 @@ int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool write)
>  		addr_ptr = &vgic->vgic_redist_base;
>  		alignment = SZ_64K;
>  		break;
> -#endif
>  	default:
>  		r = -ENODEV;
>  		goto out;
> @@ -219,15 +217,15 @@ int kvm_register_vgic_device(unsigned long type)
>  		ret = kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
>  					      KVM_DEV_TYPE_ARM_VGIC_V2);
>  		break;
> -#ifdef CONFIG_KVM_ARM_VGIC_V3
>  	case KVM_DEV_TYPE_ARM_VGIC_V3:
>  		ret = kvm_register_device_ops(&kvm_arm_vgic_v3_ops,
>  					      KVM_DEV_TYPE_ARM_VGIC_V3);
> +#ifdef CONFIG_KVM_ARM_VGIC_V3_ITS
>  		if (ret)
>  			break;
>  		ret = kvm_vgic_register_its_device();
> -		break;
>  #endif
> +		break;
>  	}
>  
>  	return ret;
> @@ -389,8 +387,6 @@ struct kvm_device_ops kvm_arm_vgic_v2_ops = {
>  
>  /* V3 ops */
>  
> -#ifdef CONFIG_KVM_ARM_VGIC_V3
> -
>  static int vgic_v3_set_attr(struct kvm_device *dev,
>  			    struct kvm_device_attr *attr)
>  {
> @@ -433,5 +429,3 @@ struct kvm_device_ops kvm_arm_vgic_v3_ops = {
>  	.get_attr = vgic_v3_get_attr,
>  	.has_attr = vgic_v3_has_attr,
>  };
> -
> -#endif /* CONFIG_KVM_ARM_VGIC_V3 */
> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> index cc20b60..4709dd65 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> @@ -42,6 +42,7 @@ u64 update_64bit_reg(u64 reg, unsigned int offset, unsigned int len,
>  	return reg | ((u64)val << lower);
>  }
>  
> +#ifdef CONFIG_KVM_ARM_VGIC_V3_ITS
>  bool vgic_has_its(struct kvm *kvm)
>  {
>  	struct vgic_dist *dist = &kvm->arch.vgic;
> @@ -51,6 +52,7 @@ bool vgic_has_its(struct kvm *kvm)
>  
>  	return dist->has_its;
>  }
> +#endif
>  
>  static unsigned long vgic_mmio_read_v3_misc(struct kvm_vcpu *vcpu,
>  					    gpa_t addr, unsigned int len)
> diff --git a/virt/kvm/arm/vgic/vgic-mmio.c b/virt/kvm/arm/vgic/vgic-mmio.c
> index 3bad3c5..e18b30d 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio.c
> @@ -550,11 +550,9 @@ int vgic_register_dist_iodev(struct kvm *kvm, gpa_t dist_base_address,
>  	case VGIC_V2:
>  		len = vgic_v2_init_dist_iodev(io_device);
>  		break;
> -#ifdef CONFIG_KVM_ARM_VGIC_V3
>  	case VGIC_V3:
>  		len = vgic_v3_init_dist_iodev(io_device);
>  		break;
> -#endif
>  	default:
>  		BUG_ON(1);
>  	}
> diff --git a/virt/kvm/arm/vgic/vgic-mmio.h b/virt/kvm/arm/vgic/vgic-mmio.h
> index 80f92ce..9098aca 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio.h
> +++ b/virt/kvm/arm/vgic/vgic-mmio.h
> @@ -162,12 +162,9 @@ unsigned int vgic_v2_init_dist_iodev(struct vgic_io_device *dev);
>  
>  unsigned int vgic_v3_init_dist_iodev(struct vgic_io_device *dev);
>  
> -#ifdef CONFIG_KVM_ARM_VGIC_V3
>  u64 vgic_sanitise_outer_cacheability(u64 reg);
>  u64 vgic_sanitise_inner_cacheability(u64 reg);
>  u64 vgic_sanitise_shareability(u64 reg);
>  u64 vgic_sanitise_field(u64 reg, u64 field_mask, int field_shift,
>  			u64 (*sanitise_fn)(u64));
>  #endif
> -
> -#endif
> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
> index 1d8e21d..633c512 100644
> --- a/virt/kvm/arm/vgic/vgic.h
> +++ b/virt/kvm/arm/vgic/vgic.h
> @@ -72,7 +72,6 @@ static inline void vgic_get_irq_kref(struct vgic_irq *irq)
>  	kref_get(&irq->refcount);
>  }
>  
> -#ifdef CONFIG_KVM_ARM_VGIC_V3
>  void vgic_v3_process_maintenance(struct kvm_vcpu *vcpu);
>  void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu);
>  void vgic_v3_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr);
> @@ -84,62 +83,13 @@ void vgic_v3_enable(struct kvm_vcpu *vcpu);
>  int vgic_v3_probe(const struct gic_kvm_info *info);
>  int vgic_v3_map_resources(struct kvm *kvm);
>  int vgic_register_redist_iodevs(struct kvm *kvm, gpa_t dist_base_address);
> +
> +#ifdef CONFIG_KVM_ARM_VGIC_V3_ITS
>  bool vgic_has_its(struct kvm *kvm);
>  int kvm_vgic_register_its_device(void);
>  void vgic_enable_lpis(struct kvm_vcpu *vcpu);
>  int vgic_its_inject_msi(struct kvm *kvm, struct kvm_msi *msi);
>  #else
> -static inline void vgic_v3_process_maintenance(struct kvm_vcpu *vcpu)
> -{
> -}
> -
> -static inline void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu)
> -{
> -}
> -
> -static inline void vgic_v3_populate_lr(struct kvm_vcpu *vcpu,
> -				       struct vgic_irq *irq, int lr)
> -{
> -}
> -
> -static inline void vgic_v3_clear_lr(struct kvm_vcpu *vcpu, int lr)
> -{
> -}
> -
> -static inline void vgic_v3_set_underflow(struct kvm_vcpu *vcpu)
> -{
> -}
> -
> -static inline
> -void vgic_v3_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr)
> -{
> -}
> -
> -static inline
> -void vgic_v3_get_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr)
> -{
> -}
> -
> -static inline void vgic_v3_enable(struct kvm_vcpu *vcpu)
> -{
> -}
> -
> -static inline int vgic_v3_probe(const struct gic_kvm_info *info)
> -{
> -	return -ENODEV;
> -}
> -
> -static inline int vgic_v3_map_resources(struct kvm *kvm)
> -{
> -	return -ENODEV;
> -}
> -
> -static inline int vgic_register_redist_iodevs(struct kvm *kvm,
> -					      gpa_t dist_base_address)
> -{
> -	return -ENODEV;
> -}
> -
>  static inline bool vgic_has_its(struct kvm *kvm)
>  {
>  	return false;
> -- 
> 1.7.9.5
> 

Thanks,
-Christoffer