Re: [PATCH v2 kvmtool 16/30] Don't ignore errors registering a device, ioport or mmio emulation

[Andre Przywara <andre.przywara@arm.com>]

On Thu, 23 Jan 2020 13:47:51 +0000
Alexandru Elisei <alexandru.elisei@arm.com> wrote:

Hi,

> An error returned by device__register, kvm__register_mmio and
> ioport__register means that the device will
> not be emulated properly. Annotate the functions with __must_check, so we
> get a compiler warning when this error is ignored.
> 
> And fix several instances where the caller returns 0 even if the
> function failed.
> 
> Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>

Looks alright, one minor nit below, with that fixed:

Reviewed-by: Andre Przywara <andre.przywara@arm.com>

> ---
>  arm/ioport.c          |  3 +-
>  hw/i8042.c            | 12 ++++++--
>  hw/vesa.c             |  4 ++-
>  include/kvm/devices.h |  3 +-
>  include/kvm/ioport.h  |  6 ++--
>  include/kvm/kvm.h     |  6 ++--
>  ioport.c              | 23 ++++++++-------
>  mips/kvm.c            |  3 +-
>  powerpc/ioport.c      |  3 +-
>  virtio/mmio.c         | 13 +++++++--
>  x86/ioport.c          | 66 ++++++++++++++++++++++++++++++++-----------
>  11 files changed, 100 insertions(+), 42 deletions(-)
> 
> diff --git a/arm/ioport.c b/arm/ioport.c
> index bdd30b6fe812..2f0feb9ab69f 100644
> --- a/arm/ioport.c
> +++ b/arm/ioport.c
> @@ -1,8 +1,9 @@
>  #include "kvm/ioport.h"
>  #include "kvm/irq.h"
>  
> -void ioport__setup_arch(struct kvm *kvm)
> +int ioport__setup_arch(struct kvm *kvm)
>  {
> +	return 0;
>  }
>  
>  void ioport__map_irq(u8 *irq)
> diff --git a/hw/i8042.c b/hw/i8042.c
> index 2d8c96e9c7e6..37a99a2dc6b8 100644
> --- a/hw/i8042.c
> +++ b/hw/i8042.c
> @@ -349,10 +349,18 @@ static struct ioport_operations kbd_ops = {
>  
>  int kbd__init(struct kvm *kvm)
>  {
> +	int r;
> +
>  	kbd_reset();
>  	state.kvm = kvm;
> -	ioport__register(kvm, I8042_DATA_REG, &kbd_ops, 2, NULL);
> -	ioport__register(kvm, I8042_COMMAND_REG, &kbd_ops, 2, NULL);
> +	r = ioport__register(kvm, I8042_DATA_REG, &kbd_ops, 2, NULL);
> +	if (r < 0)
> +		return r;
> +	r = ioport__register(kvm, I8042_COMMAND_REG, &kbd_ops, 2, NULL);
> +	if (r < 0) {
> +		ioport__unregister(kvm, I8042_DATA_REG);
> +		return r;
> +	}
>  
>  	return 0;
>  }
> diff --git a/hw/vesa.c b/hw/vesa.c
> index d8d91aa9c873..b92cc990b730 100644
> --- a/hw/vesa.c
> +++ b/hw/vesa.c
> @@ -70,7 +70,9 @@ struct framebuffer *vesa__init(struct kvm *kvm)
>  
>  	vesa_base_addr			= (u16)r;
>  	vesa_pci_device.bar[0]		= cpu_to_le32(vesa_base_addr | PCI_BASE_ADDRESS_SPACE_IO);
> -	device__register(&vesa_device);
> +	r = device__register(&vesa_device);
> +	if (r < 0)
> +		return ERR_PTR(r);
>  
>  	mem = mmap(NULL, VESA_MEM_SIZE, PROT_RW, MAP_ANON_NORESERVE, -1, 0);
>  	if (mem == MAP_FAILED)
> diff --git a/include/kvm/devices.h b/include/kvm/devices.h
> index 405f19521977..e445db6f56b1 100644
> --- a/include/kvm/devices.h
> +++ b/include/kvm/devices.h
> @@ -3,6 +3,7 @@
>  
>  #include <linux/rbtree.h>
>  #include <linux/types.h>
> +#include <linux/compiler.h>
>  
>  enum device_bus_type {
>  	DEVICE_BUS_PCI,
> @@ -18,7 +19,7 @@ struct device_header {
>  	struct rb_node		node;
>  };
>  
> -int device__register(struct device_header *dev);
> +int __must_check device__register(struct device_header *dev);
>  void device__unregister(struct device_header *dev);
>  struct device_header *device__find_dev(enum device_bus_type bus_type,
>  				       u8 dev_num);
> diff --git a/include/kvm/ioport.h b/include/kvm/ioport.h
> index 8c86b7151f25..62a719327e3f 100644
> --- a/include/kvm/ioport.h
> +++ b/include/kvm/ioport.h
> @@ -33,11 +33,11 @@ struct ioport_operations {
>  							    enum irq_type));
>  };
>  
> -void ioport__setup_arch(struct kvm *kvm);
> +int ioport__setup_arch(struct kvm *kvm);
>  void ioport__map_irq(u8 *irq);
>  
> -int ioport__register(struct kvm *kvm, u16 port, struct ioport_operations *ops,
> -			int count, void *param);
> +int __must_check ioport__register(struct kvm *kvm, u16 port, struct ioport_operations *ops,
> +				  int count, void *param);
>  int ioport__unregister(struct kvm *kvm, u16 port);
>  int ioport__init(struct kvm *kvm);
>  int ioport__exit(struct kvm *kvm);
> diff --git a/include/kvm/kvm.h b/include/kvm/kvm.h
> index c6dc6ef72d11..50119a8672eb 100644
> --- a/include/kvm/kvm.h
> +++ b/include/kvm/kvm.h
> @@ -128,9 +128,9 @@ static inline int kvm__reserve_mem(struct kvm *kvm, u64 guest_phys, u64 size)
>  				 KVM_MEM_TYPE_RESERVED);
>  }
>  
> -int kvm__register_mmio(struct kvm *kvm, u64 phys_addr, u64 phys_addr_len, bool coalesce,
> -		       void (*mmio_fn)(struct kvm_cpu *vcpu, u64 addr, u8 *data, u32 len, u8 is_write, void *ptr),
> -			void *ptr);
> +int __must_check kvm__register_mmio(struct kvm *kvm, u64 phys_addr, u64 phys_addr_len, bool coalesce,
> +				    void (*mmio_fn)(struct kvm_cpu *vcpu, u64 addr, u8 *data, u32 len, u8 is_write, void *ptr),
> +				    void *ptr);
>  bool kvm__deregister_mmio(struct kvm *kvm, u64 phys_addr);
>  void kvm__reboot(struct kvm *kvm);
>  void kvm__pause(struct kvm *kvm);
> diff --git a/ioport.c b/ioport.c
> index a72e4035881a..d224819c6e43 100644
> --- a/ioport.c
> +++ b/ioport.c
> @@ -91,16 +91,21 @@ int ioport__register(struct kvm *kvm, u16 port, struct ioport_operations *ops, i
>  	};
>  
>  	r = ioport_insert(&ioport_tree, entry);
> -	if (r < 0) {
> -		free(entry);
> -		br_write_unlock(kvm);
> -		return r;
> -	}
> -
> -	device__register(&entry->dev_hdr);
> +	if (r < 0)
> +		goto out_free;
> +	r = device__register(&entry->dev_hdr);
> +	if (r < 0)
> +		goto out_erase;
>  	br_write_unlock(kvm);
>  
>  	return port;
> +
> +out_erase:
> +	rb_int_erase(&ioport_tree, &entry->node);

To keep the abstraction, shouldn't that rather be ioport_remove() instead?

Cheers,
Andre.

> +out_free:
> +	free(entry);
> +	br_write_unlock(kvm);
> +	return r;
>  }
>  
>  int ioport__unregister(struct kvm *kvm, u16 port)
> @@ -196,9 +201,7 @@ out:
>  
>  int ioport__init(struct kvm *kvm)
>  {
> -	ioport__setup_arch(kvm);
> -
> -	return 0;
> +	return ioport__setup_arch(kvm);
>  }
>  dev_base_init(ioport__init);
>  
> diff --git a/mips/kvm.c b/mips/kvm.c
> index 211770da0d85..26355930d3b6 100644
> --- a/mips/kvm.c
> +++ b/mips/kvm.c
> @@ -100,8 +100,9 @@ void kvm__irq_trigger(struct kvm *kvm, int irq)
>  		die_perror("KVM_IRQ_LINE ioctl");
>  }
>  
> -void ioport__setup_arch(struct kvm *kvm)
> +int ioport__setup_arch(struct kvm *kvm)
>  {
> +	return 0;
>  }
>  
>  bool kvm__arch_cpu_supports_vm(void)
> diff --git a/powerpc/ioport.c b/powerpc/ioport.c
> index 58dc625c54fe..0c188b61a51a 100644
> --- a/powerpc/ioport.c
> +++ b/powerpc/ioport.c
> @@ -12,9 +12,10 @@
>  
>  #include <stdlib.h>
>  
> -void ioport__setup_arch(struct kvm *kvm)
> +int ioport__setup_arch(struct kvm *kvm)
>  {
>  	/* PPC has no legacy ioports to set up */
> +	return 0;
>  }
>  
>  void ioport__map_irq(u8 *irq)
> diff --git a/virtio/mmio.c b/virtio/mmio.c
> index 03cecc366292..5537c39367d6 100644
> --- a/virtio/mmio.c
> +++ b/virtio/mmio.c
> @@ -292,13 +292,16 @@ int virtio_mmio_init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
>  		     int device_id, int subsys_id, int class)
>  {
>  	struct virtio_mmio *vmmio = vdev->virtio;
> +	int r;
>  
>  	vmmio->addr	= virtio_mmio_get_io_space_block(VIRTIO_MMIO_IO_SIZE);
>  	vmmio->kvm	= kvm;
>  	vmmio->dev	= dev;
>  
> -	kvm__register_mmio(kvm, vmmio->addr, VIRTIO_MMIO_IO_SIZE,
> -			   false, virtio_mmio_mmio_callback, vdev);
> +	r = kvm__register_mmio(kvm, vmmio->addr, VIRTIO_MMIO_IO_SIZE,
> +			       false, virtio_mmio_mmio_callback, vdev);
> +	if (r < 0)
> +		return r;
>  
>  	vmmio->hdr = (struct virtio_mmio_hdr) {
>  		.magic		= {'v', 'i', 'r', 't'},
> @@ -313,7 +316,11 @@ int virtio_mmio_init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
>  		.data		= generate_virtio_mmio_fdt_node,
>  	};
>  
> -	device__register(&vmmio->dev_hdr);
> +	r = device__register(&vmmio->dev_hdr);
> +	if (r < 0) {
> +		kvm__deregister_mmio(kvm, vmmio->addr);
> +		return r;
> +	}
>  
>  	/*
>  	 * Instantiate guest virtio-mmio devices using kernel command line
> diff --git a/x86/ioport.c b/x86/ioport.c
> index 8572c758ed4f..7ad7b8f3f497 100644
> --- a/x86/ioport.c
> +++ b/x86/ioport.c
> @@ -69,50 +69,84 @@ void ioport__map_irq(u8 *irq)
>  {
>  }
>  
> -void ioport__setup_arch(struct kvm *kvm)
> +int ioport__setup_arch(struct kvm *kvm)
>  {
> +	int r;
> +
>  	/* Legacy ioport setup */
>  
>  	/* 0000 - 001F - DMA1 controller */
> -	ioport__register(kvm, 0x0000, &dummy_read_write_ioport_ops, 32, NULL);
> +	r = ioport__register(kvm, 0x0000, &dummy_read_write_ioport_ops, 32, NULL);
> +	if (r < 0)
> +		return r;
>  
>  	/* 0x0020 - 0x003F - 8259A PIC 1 */
> -	ioport__register(kvm, 0x0020, &dummy_read_write_ioport_ops, 2, NULL);
> +	r = ioport__register(kvm, 0x0020, &dummy_read_write_ioport_ops, 2, NULL);
> +	if (r < 0)
> +		return r;
>  
>  	/* PORT 0040-005F - PIT - PROGRAMMABLE INTERVAL TIMER (8253, 8254) */
> -	ioport__register(kvm, 0x0040, &dummy_read_write_ioport_ops, 4, NULL);
> +	r = ioport__register(kvm, 0x0040, &dummy_read_write_ioport_ops, 4, NULL);
> +	if (r < 0)
> +		return r;
>  
>  	/* 0092 - PS/2 system control port A */
> -	ioport__register(kvm, 0x0092, &ps2_control_a_ops, 1, NULL);
> +	r = ioport__register(kvm, 0x0092, &ps2_control_a_ops, 1, NULL);
> +	if (r < 0)
> +		return r;
>  
>  	/* 0x00A0 - 0x00AF - 8259A PIC 2 */
> -	ioport__register(kvm, 0x00A0, &dummy_read_write_ioport_ops, 2, NULL);
> +	r = ioport__register(kvm, 0x00A0, &dummy_read_write_ioport_ops, 2, NULL);
> +	if (r < 0)
> +		return r;
>  
>  	/* 00C0 - 001F - DMA2 controller */
> -	ioport__register(kvm, 0x00C0, &dummy_read_write_ioport_ops, 32, NULL);
> +	r = ioport__register(kvm, 0x00C0, &dummy_read_write_ioport_ops, 32, NULL);
> +	if (r < 0)
> +		return r;
>  
>  	/* PORT 00E0-00EF are 'motherboard specific' so we use them for our
>  	   internal debugging purposes.  */
> -	ioport__register(kvm, IOPORT_DBG, &debug_ops, 1, NULL);
> +	r = ioport__register(kvm, IOPORT_DBG, &debug_ops, 1, NULL);
> +	if (r < 0)
> +		return r;
>  
>  	/* PORT 00ED - DUMMY PORT FOR DELAY??? */
> -	ioport__register(kvm, 0x00ED, &dummy_write_only_ioport_ops, 1, NULL);
> +	r = ioport__register(kvm, 0x00ED, &dummy_write_only_ioport_ops, 1, NULL);
> +	if (r < 0)
> +		return r;
>  
>  	/* 0x00F0 - 0x00FF - Math co-processor */
> -	ioport__register(kvm, 0x00F0, &dummy_write_only_ioport_ops, 2, NULL);
> +	r = ioport__register(kvm, 0x00F0, &dummy_write_only_ioport_ops, 2, NULL);
> +	if (r < 0)
> +		return r;
>  
>  	/* PORT 0278-027A - PARALLEL PRINTER PORT (usually LPT1, sometimes LPT2) */
> -	ioport__register(kvm, 0x0278, &dummy_read_write_ioport_ops, 3, NULL);
> +	r = ioport__register(kvm, 0x0278, &dummy_read_write_ioport_ops, 3, NULL);
> +	if (r < 0)
> +		return r;
>  
>  	/* PORT 0378-037A - PARALLEL PRINTER PORT (usually LPT2, sometimes LPT3) */
> -	ioport__register(kvm, 0x0378, &dummy_read_write_ioport_ops, 3, NULL);
> +	r = ioport__register(kvm, 0x0378, &dummy_read_write_ioport_ops, 3, NULL);
> +	if (r < 0)
> +		return r;
>  
>  	/* PORT 03D4-03D5 - COLOR VIDEO - CRT CONTROL REGISTERS */
> -	ioport__register(kvm, 0x03D4, &dummy_read_write_ioport_ops, 1, NULL);
> -	ioport__register(kvm, 0x03D5, &dummy_write_only_ioport_ops, 1, NULL);
> +	r = ioport__register(kvm, 0x03D4, &dummy_read_write_ioport_ops, 1, NULL);
> +	if (r < 0)
> +		return r;
> +	r = ioport__register(kvm, 0x03D5, &dummy_write_only_ioport_ops, 1, NULL);
> +	if (r < 0)
> +		return r;
>  
> -	ioport__register(kvm, 0x402, &seabios_debug_ops, 1, NULL);
> +	r = ioport__register(kvm, 0x402, &seabios_debug_ops, 1, NULL);
> +	if (r < 0)
> +		return r;
>  
>  	/* 0510 - QEMU BIOS configuration register */
> -	ioport__register(kvm, 0x510, &dummy_read_write_ioport_ops, 2, NULL);
> +	r = ioport__register(kvm, 0x510, &dummy_read_write_ioport_ops, 2, NULL);
> +	if (r < 0)
> +		return r;
> +
> +	return 0;
>  }