Subject: [PATCH v4 1/5] arm/arm64: vgic-new: Implement support for userspace access

From: [email-masked] (Marc Zyngier)
Date: Mon, 12 Sep 2016 09:25:29 +0100

On 10/09/16 13:22, vijay.kilari at gmail.com wrote:
> From: Vijaya Kumar K <[email-masked]>
> 
> Read and write of some registers like ISPENDR and ICPENDR
> from userspace requires special handling when compared to
> guest access for these registers.
> 
> Refer to Documentation/virtual/kvm/devices/arm-vgic-v3.txt
> for handling of ISPENDR, ICPENDR registers handling.
> 
> Add infrastructure to support guest and userspace read
> and write for the required registers
> Also moved vgic_uaccess from vgic-mmio-v2.c to vgic-mmio.c
> 
> Signed-off-by: Vijaya Kumar K <[email-masked]>
> ---
>  virt/kvm/arm/vgic/vgic-mmio-v2.c |  25 --------
>  virt/kvm/arm/vgic/vgic-mmio-v3.c |  42 +++++++------
>  virt/kvm/arm/vgic/vgic-mmio.c    | 132 ++++++++++++++++++++++++++++++++++++---
>  virt/kvm/arm/vgic/vgic-mmio.h    |  26 ++++++++
>  4 files changed, 174 insertions(+), 51 deletions(-)
> 
> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
> index b44b359..0b32f40 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
> @@ -406,31 +406,6 @@ int vgic_v2_has_attr_regs(struct kvm_device *dev, struct kvm_device_attr *attr)
>  	return -ENXIO;
>  }
>  
> -/*
> - * When userland tries to access the VGIC register handlers, we need to
> - * create a usable struct vgic_io_device to be passed to the handlers and we
> - * have to set up a buffer similar to what would have happened if a guest MMIO
> - * access occurred, including doing endian conversions on BE systems.
> - */
> -static int vgic_uaccess(struct kvm_vcpu *vcpu, struct vgic_io_device *dev,
> -			bool is_write, int offset, u32 *val)
> -{
> -	unsigned int len = 4;
> -	u8 buf[4];
> -	int ret;
> -
> -	if (is_write) {
> -		vgic_data_host_to_mmio_bus(buf, len, *val);
> -		ret = kvm_io_gic_ops.write(vcpu, &dev->dev, offset, len, buf);
> -	} else {
> -		ret = kvm_io_gic_ops.read(vcpu, &dev->dev, offset, len, buf);
> -		if (!ret)
> -			*val = vgic_data_mmio_bus_to_host(buf, len);
> -	}
> -
> -	return ret;
> -}
> -
>  int vgic_v2_cpuif_uaccess(struct kvm_vcpu *vcpu, bool is_write,
>  			  int offset, u32 *val)
>  {
> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> index 90d8181..3b4d507 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> @@ -356,7 +356,7 @@ static void vgic_mmio_write_pendbase(struct kvm_vcpu *vcpu,
>   * We take some special care here to fix the calculation of the register
>   * offset.
>   */
> -#define REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(off, rd, wr, bpi, acc)	\
> +#define REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(off, rd, wr, ur, uw, bpi, acc) \
>  	{								\
>  		.reg_offset = off,					\
>  		.bits_per_irq = bpi,					\
> @@ -371,6 +371,8 @@ static void vgic_mmio_write_pendbase(struct kvm_vcpu *vcpu,
>  		.access_flags = acc,					\
>  		.read = rd,						\
>  		.write = wr,						\
> +		.uaccess_read = ur,					\
> +		.uaccess_write = uw,					\
>  	}
>  
>  static const struct vgic_register_region vgic_v3_dist_registers[] = {
> @@ -378,40 +380,42 @@ static const struct vgic_register_region vgic_v3_dist_registers[] = {
>  		vgic_mmio_read_v3_misc, vgic_mmio_write_v3_misc, 16,
>  		VGIC_ACCESS_32bit),
>  	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_IGROUPR,
> -		vgic_mmio_read_rao, vgic_mmio_write_wi, 1,
> +		vgic_mmio_read_rao, vgic_mmio_write_wi, NULL, NULL, 1,
>  		VGIC_ACCESS_32bit),
>  	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ISENABLER,
> -		vgic_mmio_read_enable, vgic_mmio_write_senable, 1,
> +		vgic_mmio_read_enable, vgic_mmio_write_senable, NULL, NULL, 1,
>  		VGIC_ACCESS_32bit),
>  	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ICENABLER,
> -		vgic_mmio_read_enable, vgic_mmio_write_cenable, 1,
> +		vgic_mmio_read_enable, vgic_mmio_write_cenable, NULL, NULL, 1,
>  		VGIC_ACCESS_32bit),
>  	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ISPENDR,
> -		vgic_mmio_read_pending, vgic_mmio_write_spending, 1,
> +		vgic_mmio_read_pending, vgic_mmio_write_spending,
> +		vgic_uaccess_read_pending, vgic_uaccess_write_pending, 1,
>  		VGIC_ACCESS_32bit),
>  	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ICPENDR,
> -		vgic_mmio_read_pending, vgic_mmio_write_cpending, 1,
> +		vgic_mmio_read_pending, vgic_mmio_write_cpending,
> +		vgic_uaccess_read_pending, vgic_mmio_write_wi, 1,
>  		VGIC_ACCESS_32bit),
>  	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ISACTIVER,
> -		vgic_mmio_read_active, vgic_mmio_write_sactive, 1,
> +		vgic_mmio_read_active, vgic_mmio_write_sactive, NULL, NULL, 1,
>  		VGIC_ACCESS_32bit),
>  	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ICACTIVER,
> -		vgic_mmio_read_active, vgic_mmio_write_cactive, 1,
> +		vgic_mmio_read_active, vgic_mmio_write_cactive, NULL, NULL, 1,
>  		VGIC_ACCESS_32bit),
>  	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_IPRIORITYR,
> -		vgic_mmio_read_priority, vgic_mmio_write_priority, 8,
> -		VGIC_ACCESS_32bit | VGIC_ACCESS_8bit),
> +		vgic_mmio_read_priority, vgic_mmio_write_priority, NULL, NULL,
> +		8, VGIC_ACCESS_32bit | VGIC_ACCESS_8bit),
>  	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ITARGETSR,
> -		vgic_mmio_read_raz, vgic_mmio_write_wi, 8,
> +		vgic_mmio_read_raz, vgic_mmio_write_wi, NULL, NULL, 8,
>  		VGIC_ACCESS_32bit | VGIC_ACCESS_8bit),
>  	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ICFGR,
> -		vgic_mmio_read_config, vgic_mmio_write_config, 2,
> +		vgic_mmio_read_config, vgic_mmio_write_config, NULL, NULL, 2,
>  		VGIC_ACCESS_32bit),
>  	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_IGRPMODR,
> -		vgic_mmio_read_raz, vgic_mmio_write_wi, 1,
> +		vgic_mmio_read_raz, vgic_mmio_write_wi, NULL, NULL, 1,
>  		VGIC_ACCESS_32bit),
>  	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_IROUTER,
> -		vgic_mmio_read_irouter, vgic_mmio_write_irouter, 64,
> +		vgic_mmio_read_irouter, vgic_mmio_write_irouter, NULL, NULL, 64,
>  		VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
>  	REGISTER_DESC_WITH_LENGTH(GICD_IDREGS,
>  		vgic_mmio_read_v3_idregs, vgic_mmio_write_wi, 48,
> @@ -449,11 +453,13 @@ static const struct vgic_register_region vgic_v3_sgibase_registers[] = {
>  	REGISTER_DESC_WITH_LENGTH(GICR_ICENABLER0,
>  		vgic_mmio_read_enable, vgic_mmio_write_cenable, 4,
>  		VGIC_ACCESS_32bit),
> -	REGISTER_DESC_WITH_LENGTH(GICR_ISPENDR0,
> -		vgic_mmio_read_pending, vgic_mmio_write_spending, 4,
> +	REGISTER_DESC_WITH_LENGTH_UACCESS(GICR_ISPENDR0,
> +		vgic_mmio_read_pending, vgic_mmio_write_spending,
> +		vgic_uaccess_read_pending, vgic_uaccess_write_pending, 4,
>  		VGIC_ACCESS_32bit),
> -	REGISTER_DESC_WITH_LENGTH(GICR_ICPENDR0,
> -		vgic_mmio_read_pending, vgic_mmio_write_cpending, 4,
> +	REGISTER_DESC_WITH_LENGTH_UACCESS(GICR_ICPENDR0,
> +		vgic_mmio_read_pending, vgic_mmio_write_cpending,
> +		vgic_uaccess_read_pending, vgic_mmio_write_wi, 4,
>  		VGIC_ACCESS_32bit),
>  	REGISTER_DESC_WITH_LENGTH(GICR_ISACTIVER0,
>  		vgic_mmio_read_active, vgic_mmio_write_sactive, 4,
> diff --git a/virt/kvm/arm/vgic/vgic-mmio.c b/virt/kvm/arm/vgic/vgic-mmio.c
> index 3bad3c5..99d88a6 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio.c
> @@ -100,6 +100,60 @@ void vgic_mmio_write_cenable(struct kvm_vcpu *vcpu,
>  	}
>  }
>  
> +unsigned long vgic_uaccess_read_pending(struct kvm_vcpu *vcpu,
> +					gpa_t addr, unsigned int len)
> +{
> +	u32 intid = VGIC_ADDR_TO_INTID(addr, 1);
> +	u32 value = 0;
> +	int i;
> +
> +	/*
> +	 * A level triggerred interrupt pending state is latched in both
> +	 * "soft_pending" and "line_level" variables. Userspace will save
> +	 * and restore soft_pending and line_level separately.
> +	 * Refer to Documentation/virtual/kvm/devices/arm-vgic-v3.txt
> +	 * handling of ISPENDR and ICPENDR.
> +	 */
> +	for (i = 0; i < len * 8; i++) {
> +		struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
> +
> +		if (irq->config == VGIC_CONFIG_LEVEL && irq->soft_pending)
> +			value |= (1U << i);
> +		if (irq->config == VGIC_CONFIG_EDGE && irq->pending)
> +			value |= (1U << i);

Please use vgic_put_irq(). It may not be strictly required@the moment
for non-LPIs, but we may use it in the future (and I don't want to have
to look for those imbalanced calls).

> +	}
> +
> +	return value;
> +}
> +
> +void vgic_uaccess_write_pending(struct kvm_vcpu *vcpu,
> +				gpa_t addr, unsigned int len,
> +				unsigned long val)
> +{
> +	u32 intid = VGIC_ADDR_TO_INTID(addr, 1);
> +	int i;
> +
> +	for (i = 0; i < len * 8; i++) {
> +		struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
> +
> +		spin_lock(&irq->irq_lock);
> +		if (test_bit(i, &val)) {
> +			irq->pending = true;
> +			irq->soft_pending = true;
> +			vgic_queue_irq_unlock(vcpu->kvm, irq);
> +		} else {
> +			irq->soft_pending = false;
> +			if (irq->config == VGIC_CONFIG_EDGE ||
> +			    (irq->config == VGIC_CONFIG_LEVEL &&
> +			    !irq->line_level))
> +				irq->pending = false;
> +			spin_unlock(&irq->irq_lock);
> +		}
> +
> +		vgic_put_irq(vcpu->kvm, irq);
> +	}
> +}
> +

These two functions only seems to be called from the GICv3 code. What is
the rational for making them globally accessible? Or should they also be
wired into the GICv2 code?

>  unsigned long vgic_mmio_read_pending(struct kvm_vcpu *vcpu,
>  				     gpa_t addr, unsigned int len)
>  {
> @@ -468,6 +522,73 @@ static bool check_region(const struct vgic_register_region *region,
>  	return false;
>  }
>  
> +static const struct vgic_register_region *
> +	vgic_get_mmio_region(struct vgic_io_device *iodev, gpa_t addr, int len)

nit: spurious tab?

> +{
> +	const struct vgic_register_region *region;
> +
> +	region = vgic_find_mmio_region(iodev->regions, iodev->nr_regions,
> +				       addr - iodev->base_addr);
> +	if (!region || !check_region(region, addr, len))
> +		return NULL;
> +
> +	return region;
> +}
> +
> +static int vgic_uaccess_read(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
> +			     gpa_t addr, u32 *val)
> +{
> +	struct vgic_io_device *iodev = kvm_to_vgic_iodev(dev);
> +	const struct vgic_register_region *region;
> +	struct kvm_vcpu *r_vcpu;
> +
> +	region = vgic_get_mmio_region(iodev, addr, sizeof(u32));
> +	if (!region) {
> +		*val = 0;
> +		return 0;
> +	}
> +
> +	r_vcpu = iodev->redist_vcpu ? iodev->redist_vcpu : vcpu;
> +	if (region->uaccess_read)
> +		*val = region->uaccess_read(r_vcpu, addr, sizeof(u32));
> +	else
> +		*val = region->read(r_vcpu, addr, sizeof(u32));
> +
> +	return 0;
> +}
> +
> +static int vgic_uaccess_write(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
> +			      gpa_t addr, const u32 *val)
> +{
> +	struct vgic_io_device *iodev = kvm_to_vgic_iodev(dev);
> +	const struct vgic_register_region *region;
> +	struct kvm_vcpu *r_vcpu;
> +
> +	region = vgic_get_mmio_region(iodev, addr, sizeof(u32));
> +	if (!region)
> +		return 0;
> +
> +	r_vcpu = iodev->redist_vcpu ? iodev->redist_vcpu : vcpu;
> +	if (region->uaccess_write)
> +		region->uaccess_write(r_vcpu, addr, sizeof(u32), *val);
> +	else
> +		region->write(r_vcpu, addr, sizeof(u32), *val);
> +
> +	return 0;
> +}
> +
> +/*
> + * Userland access to VGIC registers.
> + */
> +int vgic_uaccess(struct kvm_vcpu *vcpu, struct vgic_io_device *dev,
> +		 bool is_write, int offset, u32 *val)
> +{
> +	if (is_write)
> +		return vgic_uaccess_write(vcpu, &dev->dev, offset, val);
> +	else
> +		return vgic_uaccess_read(vcpu, &dev->dev, offset, val);
> +}
> +
>  static int dispatch_mmio_read(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
>  			      gpa_t addr, int len, void *val)
>  {
> @@ -475,9 +596,8 @@ static int dispatch_mmio_read(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
>  	const struct vgic_register_region *region;
>  	unsigned long data = 0;
>  
> -	region = vgic_find_mmio_region(iodev->regions, iodev->nr_regions,
> -				       addr - iodev->base_addr);
> -	if (!region || !check_region(region, addr, len)) {
> +	region = vgic_get_mmio_region(iodev, addr, len);
> +	if (!region) {
>  		memset(val, 0, len);
>  		return 0;
>  	}
> @@ -508,14 +628,10 @@ static int dispatch_mmio_write(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
>  	const struct vgic_register_region *region;
>  	unsigned long data = vgic_data_mmio_bus_to_host(val, len);
>  
> -	region = vgic_find_mmio_region(iodev->regions, iodev->nr_regions,
> -				       addr - iodev->base_addr);
> +	region = vgic_get_mmio_region(iodev, addr, len);
>  	if (!region)
>  		return 0;
>  
> -	if (!check_region(region, addr, len))
> -		return 0;
> -
>  	switch (iodev->iodev_type) {
>  	case IODEV_CPUIF:
>  		region->write(vcpu, addr, len, data);
> diff --git a/virt/kvm/arm/vgic/vgic-mmio.h b/virt/kvm/arm/vgic/vgic-mmio.h
> index 0b3ecf9..3435f28 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio.h
> +++ b/virt/kvm/arm/vgic/vgic-mmio.h
> @@ -34,6 +34,10 @@ struct vgic_register_region {
>  				  gpa_t addr, unsigned int len,
>  				  unsigned long val);
>  	};
> +	unsigned long (*uaccess_read)(struct kvm_vcpu *vcpu, gpa_t addr,
> +				      unsigned int len);
> +	void (*uaccess_write)(struct kvm_vcpu *vcpu, gpa_t addr,
> +			      unsigned int len, unsigned long val);
>  };
>  
>  extern struct kvm_io_device_ops kvm_io_gic_ops;
> @@ -86,6 +90,18 @@ extern struct kvm_io_device_ops kvm_io_gic_ops;
>  		.write = wr,						\
>  	}
>  
> +#define REGISTER_DESC_WITH_LENGTH_UACCESS(off, rd, wr, urd, uwr, length, acc) \
> +	{								\
> +		.reg_offset = off,					\
> +		.bits_per_irq = 0,					\
> +		.len = length,						\
> +		.access_flags = acc,					\
> +		.read = rd,						\
> +		.write = wr,						\
> +		.uaccess_read = urd,					\
> +		.uaccess_write = uwr,					\
> +	}
> +
>  int kvm_vgic_register_mmio_region(struct kvm *kvm, struct kvm_vcpu *vcpu,
>  				  struct vgic_register_region *reg_desc,
>  				  struct vgic_io_device *region,
> @@ -122,6 +138,13 @@ void vgic_mmio_write_cenable(struct kvm_vcpu *vcpu,
>  			     gpa_t addr, unsigned int len,
>  			     unsigned long val);
>  
> +unsigned long vgic_uaccess_read_pending(struct kvm_vcpu *vcpu,
> +					gpa_t addr, unsigned int len);
> +
> +void vgic_uaccess_write_pending(struct kvm_vcpu *vcpu,
> +				gpa_t addr, unsigned int len,
> +				unsigned long val);
> +
>  unsigned long vgic_mmio_read_pending(struct kvm_vcpu *vcpu,
>  				     gpa_t addr, unsigned int len);
>  
> @@ -158,6 +181,9 @@ void vgic_mmio_write_config(struct kvm_vcpu *vcpu,
>  			    gpa_t addr, unsigned int len,
>  			    unsigned long val);
>  
> +int vgic_uaccess(struct kvm_vcpu *vcpu, struct vgic_io_device *dev,
> +		 bool is_write, int offset, u32 *val);
> +
>  unsigned int vgic_v2_init_dist_iodev(struct vgic_io_device *dev);
>  
>  unsigned int vgic_v3_init_dist_iodev(struct vgic_io_device *dev);
> 

Thanks,

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