Re: [PATCH v2 12/15] KVM: arm64: add a new vcpu device control group for SPEv1

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Hi Sudeep,

On 23/05/2019 11:34, Sudeep Holla wrote:
> To configure the virtual SPEv1 overflow interrupt number, we use the
> vcpu kvm_device ioctl, encapsulating the KVM_ARM_VCPU_SPE_V1_IRQ
> attribute within the KVM_ARM_VCPU_SPE_V1_CTRL group.
> 
> After configuring the SPEv1, call the vcpu ioctl with attribute
> KVM_ARM_VCPU_SPE_V1_INIT to initialize the SPEv1.
> 
> Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
> ---
>  Documentation/virtual/kvm/devices/vcpu.txt |  28 ++++
>  arch/arm64/include/asm/kvm_host.h          |   2 +-
>  arch/arm64/include/uapi/asm/kvm.h          |   4 +
>  arch/arm64/kvm/Makefile                    |   1 +
>  arch/arm64/kvm/guest.c                     |   9 ++
>  arch/arm64/kvm/reset.c                     |   3 +
>  include/kvm/arm_spe.h                      |  35 +++++
>  include/uapi/linux/kvm.h                   |   1 +
>  virt/kvm/arm/arm.c                         |   1 +
>  virt/kvm/arm/spe.c                         | 163 +++++++++++++++++++++
>  10 files changed, 246 insertions(+), 1 deletion(-)
>  create mode 100644 virt/kvm/arm/spe.c
> 
> diff --git a/Documentation/virtual/kvm/devices/vcpu.txt b/Documentation/virtual/kvm/devices/vcpu.txt
> index 2b5dab16c4f2..d1ece488aeee 100644
> --- a/Documentation/virtual/kvm/devices/vcpu.txt
> +++ b/Documentation/virtual/kvm/devices/vcpu.txt
> @@ -60,3 +60,31 @@ time to use the number provided for a given timer, overwriting any previously
>  configured values on other VCPUs.  Userspace should configure the interrupt
>  numbers on at least one VCPU after creating all VCPUs and before running any
>  VCPUs.
> +
> +3. GROUP: KVM_ARM_VCPU_SPE_V1_CTRL
> +Architectures: ARM64
> +
> +1.1. ATTRIBUTE: KVM_ARM_VCPU_SPE_V1_IRQ
> +Parameters: in kvm_device_attr.addr the address for SPE buffer overflow interrupt
> +	    is a pointer to an int
> +Returns: -EBUSY: The SPE overflow interrupt is already set
> +         -ENXIO: The overflow interrupt not set when attempting to get it
> +         -ENODEV: SPEv1 not supported
> +         -EINVAL: Invalid SPE overflow interrupt number supplied or
> +                  trying to set the IRQ number without using an in-kernel
> +                  irqchip.
> +
> +A value describing the SPEv1 (Statistical Profiling Extension v1) overflow
> +interrupt number for this vcpu. This interrupt should be PPI and the interrupt
> +type and number must be same for each vcpu.
> +
> +1.2 ATTRIBUTE: KVM_ARM_VCPU_SPE_V1_INIT
> +Parameters: no additional parameter in kvm_device_attr.addr
> +Returns: -ENODEV: SPEv1 not supported or GIC not initialized
> +         -ENXIO: SPEv1 not properly configured or in-kernel irqchip not
> +                 configured as required prior to calling this attribute
> +         -EBUSY: SPEv1 already initialized
> +
> +Request the initialization of the SPEv1.  If using the SPEv1 with an in-kernel
> +virtual GIC implementation, this must be done after initializing the in-kernel
> +irqchip.
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 6921fdfd477b..fc4ead0774b3 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -50,7 +50,7 @@
>  
>  #define KVM_MAX_VCPUS VGIC_V3_MAX_CPUS
>  
> -#define KVM_VCPU_MAX_FEATURES 7
> +#define KVM_VCPU_MAX_FEATURES 8
>  
>  #define KVM_REQ_SLEEP \
>  	KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
> index 7b7ac0f6cec9..4c9e168de896 100644
> --- a/arch/arm64/include/uapi/asm/kvm.h
> +++ b/arch/arm64/include/uapi/asm/kvm.h
> @@ -106,6 +106,7 @@ struct kvm_regs {
>  #define KVM_ARM_VCPU_SVE		4 /* enable SVE for this CPU */
>  #define KVM_ARM_VCPU_PTRAUTH_ADDRESS	5 /* VCPU uses address authentication */
>  #define KVM_ARM_VCPU_PTRAUTH_GENERIC	6 /* VCPU uses generic authentication */
> +#define KVM_ARM_VCPU_SPE_V1		7 /* Support guest SPEv1 */
>  
>  struct kvm_vcpu_init {
>  	__u32 target;
> @@ -306,6 +307,9 @@ struct kvm_vcpu_events {
>  #define KVM_ARM_VCPU_TIMER_CTRL		1
>  #define   KVM_ARM_VCPU_TIMER_IRQ_VTIMER		0
>  #define   KVM_ARM_VCPU_TIMER_IRQ_PTIMER		1
> +#define KVM_ARM_VCPU_SPE_V1_CTRL	2
> +#define   KVM_ARM_VCPU_SPE_V1_IRQ	0
> +#define   KVM_ARM_VCPU_SPE_V1_INIT	1
>  
>  /* KVM_IRQ_LINE irq field index values */
>  #define KVM_ARM_IRQ_TYPE_SHIFT		24
> diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
> index 3ac1a64d2fb9..1ba6154dd8e1 100644
> --- a/arch/arm64/kvm/Makefile
> +++ b/arch/arm64/kvm/Makefile
> @@ -35,3 +35,4 @@ kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-debug.o
>  kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/irqchip.o
>  kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/arch_timer.o
>  kvm-$(CONFIG_KVM_ARM_PMU) += $(KVM)/arm/pmu.o
> +kvm-$(CONFIG_KVM_ARM_SPE) += $(KVM)/arm/spe.o
> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> index 3ae2f82fca46..02c28a7eb332 100644
> --- a/arch/arm64/kvm/guest.c
> +++ b/arch/arm64/kvm/guest.c
> @@ -848,6 +848,9 @@ int kvm_arm_vcpu_arch_set_attr(struct kvm_vcpu *vcpu,
>  	case KVM_ARM_VCPU_TIMER_CTRL:
>  		ret = kvm_arm_timer_set_attr(vcpu, attr);
>  		break;
> +	case KVM_ARM_VCPU_SPE_V1_CTRL:
> +		ret = kvm_arm_spe_v1_set_attr(vcpu, attr);
> +		break;
>  	default:
>  		ret = -ENXIO;
>  		break;
> @@ -868,6 +871,9 @@ int kvm_arm_vcpu_arch_get_attr(struct kvm_vcpu *vcpu,
>  	case KVM_ARM_VCPU_TIMER_CTRL:
>  		ret = kvm_arm_timer_get_attr(vcpu, attr);
>  		break;
> +	case KVM_ARM_VCPU_SPE_V1_CTRL:
> +		ret = kvm_arm_spe_v1_get_attr(vcpu, attr);
> +		break;
>  	default:
>  		ret = -ENXIO;
>  		break;
> @@ -888,6 +894,9 @@ int kvm_arm_vcpu_arch_has_attr(struct kvm_vcpu *vcpu,
>  	case KVM_ARM_VCPU_TIMER_CTRL:
>  		ret = kvm_arm_timer_has_attr(vcpu, attr);
>  		break;
> +	case KVM_ARM_VCPU_SPE_V1_CTRL:
> +		ret = kvm_arm_spe_v1_has_attr(vcpu, attr);
> +		break;
>  	default:
>  		ret = -ENXIO;
>  		break;
> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
> index 1140b4485575..33ce5248613e 100644
> --- a/arch/arm64/kvm/reset.c
> +++ b/arch/arm64/kvm/reset.c
> @@ -91,6 +91,9 @@ int kvm_arch_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_ARM_INJECT_SERROR_ESR:
>  		r = cpus_have_const_cap(ARM64_HAS_RAS_EXTN);
>  		break;
> +	case KVM_CAP_ARM_SPE_V1:
> +		r = kvm_arm_support_spe_v1();
> +		break;
>  	case KVM_CAP_SET_GUEST_DEBUG:
>  	case KVM_CAP_VCPU_ATTRIBUTES:
>  		r = 1;
> diff --git a/include/kvm/arm_spe.h b/include/kvm/arm_spe.h
> index fdcb0df1e0fd..8c2e8f10a965 100644
> --- a/include/kvm/arm_spe.h
> +++ b/include/kvm/arm_spe.h
> @@ -19,6 +19,9 @@ struct kvm_spe {
>  #ifdef CONFIG_KVM_ARM_SPE
>  
>  #define kvm_arm_spe_v1_ready(v)		((v)->arch.spe.ready)
> +#define kvm_arm_spe_irq_initialized(v)		\
> +	((v)->arch.spe.irq >= VGIC_NR_SGIS &&	\
> +	(v)->arch.spe.irq <= VGIC_MAX_PRIVATE)
>  
>  static inline bool kvm_arm_support_spe_v1(void)
>  {
> @@ -27,10 +30,42 @@ static inline bool kvm_arm_support_spe_v1(void)
>  	return !!cpuid_feature_extract_unsigned_field(dfr0,
>  						      ID_AA64DFR0_PMSVER_SHIFT);
>  }
> +
> +int kvm_arm_spe_v1_set_attr(struct kvm_vcpu *vcpu,
> +			    struct kvm_device_attr *attr);
> +int kvm_arm_spe_v1_get_attr(struct kvm_vcpu *vcpu,
> +			    struct kvm_device_attr *attr);
> +int kvm_arm_spe_v1_has_attr(struct kvm_vcpu *vcpu,
> +			    struct kvm_device_attr *attr);
> +int kvm_arm_spe_v1_enable(struct kvm_vcpu *vcpu);
>  #else
>  
>  #define kvm_arm_spe_v1_ready(v)		(false)
>  #define kvm_arm_support_spe_v1()	(false)
> +#define kvm_arm_spe_irq_initialized(v)	(false)
> +
> +static inline int kvm_arm_spe_v1_set_attr(struct kvm_vcpu *vcpu,
> +					  struct kvm_device_attr *attr)
> +{
> +	return -ENXIO;
> +}
> +
> +static inline int kvm_arm_spe_v1_get_attr(struct kvm_vcpu *vcpu,
> +					  struct kvm_device_attr *attr)
> +{
> +	return -ENXIO;
> +}
> +
> +static inline int kvm_arm_spe_v1_has_attr(struct kvm_vcpu *vcpu,
> +					  struct kvm_device_attr *attr)
> +{
> +	return -ENXIO;
> +}
> +
> +static inline int kvm_arm_spe_v1_enable(struct kvm_vcpu *vcpu)
> +{
> +	return 0;
> +}
>  #endif /* CONFIG_KVM_ARM_SPE */
>  
>  #endif /* __ASM_ARM_KVM_SPE_H */
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 2fe12b40d503..698bcc2f96e3 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -993,6 +993,7 @@ struct kvm_ppc_resize_hpt {
>  #define KVM_CAP_ARM_SVE 170
>  #define KVM_CAP_ARM_PTRAUTH_ADDRESS 171
>  #define KVM_CAP_ARM_PTRAUTH_GENERIC 172
> +#define KVM_CAP_ARM_SPE_V1 173
>  
>  #ifdef KVM_CAP_IRQ_ROUTING
>  
> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
> index 90cedebaeb94..c5b711ef1cf8 100644
> --- a/virt/kvm/arm/arm.c
> +++ b/virt/kvm/arm/arm.c
> @@ -34,6 +34,7 @@
>  #include <trace/events/kvm.h>
>  #include <kvm/arm_pmu.h>
>  #include <kvm/arm_psci.h>
> +#include <kvm/arm_spe.h>
>  
>  #define CREATE_TRACE_POINTS
>  #include "trace.h"
> diff --git a/virt/kvm/arm/spe.c b/virt/kvm/arm/spe.c
> new file mode 100644
> index 000000000000..87f02ed92426
> --- /dev/null
> +++ b/virt/kvm/arm/spe.c
> @@ -0,0 +1,163 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2018 ARM Ltd.
> + */
> +
> +#include <linux/cpu.h>
> +#include <linux/kvm.h>
> +#include <linux/kvm_host.h>
> +#include <linux/uaccess.h>
> +#include <asm/kvm_emulate.h>
> +#include <kvm/arm_spe.h>
> +#include <kvm/arm_vgic.h>
> +
> +int kvm_arm_spe_v1_enable(struct kvm_vcpu *vcpu)
> +{
> +	if (!vcpu->arch.spe.created)
> +		return 0;
> +
> +	/*
> +	 * A valid interrupt configuration for the SPE is either to have a
> +	 * properly configured interrupt number and using an in-kernel irqchip.
> +	 */
> +	if (irqchip_in_kernel(vcpu->kvm)) {
> +		int irq = vcpu->arch.spe.irq;
> +
> +		if (!kvm_arm_spe_irq_initialized(vcpu))
> +			return -EINVAL;
> +
> +		if (!irq_is_ppi(irq))
> +			return -EINVAL;
> +	}
> +
> +	vcpu->arch.spe.ready = true;

I don't think we should entertain the idea of using SPE without an
in-kernel irqchip, nor on systems that do not have a GIC.

But there is a more fundamental issue here: I do not see how the SPE
interrupt get injected in the guest. I've gone through the series twice,
and I can't see how we go from a physical interrupt triggered by the HW
on the host to a virtual interrupt injected in the guest.

What am I missing?

Thanks,

	M.

> +
> +	return 0;
> +}
> +
> +static int kvm_arm_spe_v1_init(struct kvm_vcpu *vcpu)
> +{
> +	if (!kvm_arm_support_spe_v1())
> +		return -ENODEV;
> +
> +	if (!test_bit(KVM_ARM_VCPU_SPE_V1, vcpu->arch.features))
> +		return -ENXIO;
> +
> +	if (vcpu->arch.spe.created)
> +		return -EBUSY;
> +
> +	if (irqchip_in_kernel(vcpu->kvm)) {
> +		int ret;
> +
> +		/*
> +		 * If using the SPE with an in-kernel virtual GIC
> +		 * implementation, we require the GIC to be already
> +		 * initialized when initializing the SPE.
> +		 */
> +		if (!vgic_initialized(vcpu->kvm))
> +			return -ENODEV;
> +
> +		ret = kvm_vgic_set_owner(vcpu, vcpu->arch.spe.irq,
> +					 &vcpu->arch.spe);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	vcpu->arch.spe.created = true;
> +	return 0;
> +}
> +
> +/*
> + * For one VM the interrupt type must be same for each vcpu.
> + * As a PPI, the interrupt number is the same for all vcpus,
> + * while as an SPI it must be a separate number per vcpu.
> + */
> +static bool spe_irq_is_valid(struct kvm *kvm, int irq)
> +{
> +	int i;
> +	struct kvm_vcpu *vcpu;
> +
> +	kvm_for_each_vcpu(i, vcpu, kvm) {
> +		if (!kvm_arm_spe_irq_initialized(vcpu))
> +			continue;
> +
> +		if (vcpu->arch.spe.irq != irq)
> +			return false;
> +	}
> +
> +	return true;
> +}
> +
> +int kvm_arm_spe_v1_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
> +{
> +	switch (attr->attr) {
> +	case KVM_ARM_VCPU_SPE_V1_IRQ: {
> +		int __user *uaddr = (int __user *)(long)attr->addr;
> +		int irq;
> +
> +		if (!irqchip_in_kernel(vcpu->kvm))
> +			return -EINVAL;
> +
> +		if (!test_bit(KVM_ARM_VCPU_SPE_V1, vcpu->arch.features))
> +			return -ENODEV;
> +
> +		if (get_user(irq, uaddr))
> +			return -EFAULT;
> +
> +		/* The SPE overflow interrupt can be a PPI only */
> +		if (!(irq_is_ppi(irq)))
> +			return -EINVAL;
> +
> +		if (!spe_irq_is_valid(vcpu->kvm, irq))
> +			return -EINVAL;
> +
> +		if (kvm_arm_spe_irq_initialized(vcpu))
> +			return -EBUSY;
> +
> +		kvm_debug("Set kvm ARM SPE irq: %d\n", irq);
> +		vcpu->arch.spe.irq = irq;
> +		return 0;
> +	}
> +	case KVM_ARM_VCPU_SPE_V1_INIT:
> +		return kvm_arm_spe_v1_init(vcpu);
> +	}
> +
> +	return -ENXIO;
> +}
> +
> +int kvm_arm_spe_v1_get_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
> +{
> +	switch (attr->attr) {
> +	case KVM_ARM_VCPU_SPE_V1_IRQ: {
> +		int __user *uaddr = (int __user *)(long)attr->addr;
> +		int irq;
> +
> +		if (!irqchip_in_kernel(vcpu->kvm))
> +			return -EINVAL;
> +
> +		if (!test_bit(KVM_ARM_VCPU_SPE_V1, vcpu->arch.features))
> +			return -ENODEV;
> +
> +		if (!kvm_arm_spe_irq_initialized(vcpu))
> +			return -ENXIO;
> +
> +		irq = vcpu->arch.spe.irq;
> +		return put_user(irq, uaddr);
> +	}
> +	}
> +
> +	return -ENXIO;
> +}
> +
> +int kvm_arm_spe_v1_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
> +{
> +	switch (attr->attr) {
> +	case KVM_ARM_VCPU_SPE_V1_IRQ:
> +	case KVM_ARM_VCPU_SPE_V1_INIT:
> +		if (kvm_arm_support_spe_v1() &&
> +		    test_bit(KVM_ARM_VCPU_SPE_V1, vcpu->arch.features))
> +			return 0;
> +	}
> +
> +	return -ENXIO;
> +}
> 


-- 
Jazz is not dead. It just smells funny...
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