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

Marc Zyngier
2019-05-24T10:38:06Z

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@arm.com>
> ---
> 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...