[PATCH kvmtool 07/16] pci: Fix ioport allocation size

[Alexandru Elisei <alexandru.elisei@arm.com>]

From: Julien Thierry <julien.thierry@arm.com>

The PCI Local Bus Specification, Rev. 3.0, Section 6.2.5.1. "Address Maps"
states: "Devices that map control functions into I/O Space must not consume
more than 256 bytes per I/O Base Address register."

Yet all the PCI devices allocate IO ports of IOPORT_SIZE (= 1024 bytes).

Fix this by having PCI devices use 256 bytes ports for IO BARs.

There is no hard requirement on the size of the memory region described
by memory BARs. However, the region must be big enough to hold the
virtio common interface described in [1], which is 20 bytes, and other
MSI-X and/or device specific configuration. To be consistent, let's also
limit the memory region described by BAR1 to 256. This is the same size
used by BAR2 for each of the two MSI-X vectors.

[1] VIRTIO Version 1.0 Committee Specification 04, section 4.4.8.

Cc: julien.thierry.kdev@gmail.com
Signed-off-by: Julien Thierry <julien.thierry@arm.com>
[Added rationale for changing BAR1 size to PCI_IO_SIZE]
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
 hw/vesa.c            |  4 ++--
 include/kvm/ioport.h |  1 -
 pci.c                |  2 +-
 virtio/pci.c         | 15 +++++++--------
 4 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/hw/vesa.c b/hw/vesa.c
index 70ab59974f76..0191e9264666 100644
--- a/hw/vesa.c
+++ b/hw/vesa.c
@@ -62,8 +62,8 @@ struct framebuffer *vesa__init(struct kvm *kvm)
 
 	if (!kvm->cfg.vnc && !kvm->cfg.sdl && !kvm->cfg.gtk)
 		return NULL;
-	r = pci_get_io_port_block(IOPORT_SIZE);
-	r = ioport__register(kvm, r, &vesa_io_ops, IOPORT_SIZE, NULL);
+	r = pci_get_io_port_block(PCI_IO_SIZE);
+	r = ioport__register(kvm, r, &vesa_io_ops, PCI_IO_SIZE, NULL);
 	if (r < 0)
 		return ERR_PTR(r);
 
diff --git a/include/kvm/ioport.h b/include/kvm/ioport.h
index b10fcd5b4412..8c86b7151f25 100644
--- a/include/kvm/ioport.h
+++ b/include/kvm/ioport.h
@@ -14,7 +14,6 @@
 
 /* some ports we reserve for own use */
 #define IOPORT_DBG			0xe0
-#define IOPORT_SIZE			0x400
 
 struct kvm;
 
diff --git a/pci.c b/pci.c
index 32a07335a765..b4677434c50c 100644
--- a/pci.c
+++ b/pci.c
@@ -20,7 +20,7 @@ static u16 io_port_blocks		= PCI_IOPORT_START;
 
 u16 pci_get_io_port_block(u32 size)
 {
-	u16 port = ALIGN(io_port_blocks, IOPORT_SIZE);
+	u16 port = ALIGN(io_port_blocks, PCI_IO_SIZE);
 
 	io_port_blocks = port + size;
 	return port;
diff --git a/virtio/pci.c b/virtio/pci.c
index d73414abde05..eeb5b5efa6e1 100644
--- a/virtio/pci.c
+++ b/virtio/pci.c
@@ -421,7 +421,7 @@ static void virtio_pci__io_mmio_callback(struct kvm_cpu *vcpu,
 {
 	struct virtio_pci *vpci = ptr;
 	int direction = is_write ? KVM_EXIT_IO_OUT : KVM_EXIT_IO_IN;
-	u16 port = vpci->port_addr + (addr & (IOPORT_SIZE - 1));
+	u16 port = vpci->port_addr + (addr & (PCI_IO_SIZE - 1));
 
 	kvm__emulate_io(vcpu, port, data, direction, len, 1);
 }
@@ -435,17 +435,16 @@ int virtio_pci__init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
 	vpci->kvm = kvm;
 	vpci->dev = dev;
 
-	BUILD_BUG_ON(!is_power_of_two(IOPORT_SIZE));
 	BUILD_BUG_ON(!is_power_of_two(PCI_IO_SIZE));
 
-	r = pci_get_io_port_block(IOPORT_SIZE);
-	r = ioport__register(kvm, r, &virtio_pci__io_ops, IOPORT_SIZE, vdev);
+	r = pci_get_io_port_block(PCI_IO_SIZE);
+	r = ioport__register(kvm, r, &virtio_pci__io_ops, PCI_IO_SIZE, vdev);
 	if (r < 0)
 		return r;
 	vpci->port_addr = (u16)r;
 
-	vpci->mmio_addr = pci_get_mmio_block(IOPORT_SIZE);
-	r = kvm__register_mmio(kvm, vpci->mmio_addr, IOPORT_SIZE, false,
+	vpci->mmio_addr = pci_get_mmio_block(PCI_IO_SIZE);
+	r = kvm__register_mmio(kvm, vpci->mmio_addr, PCI_IO_SIZE, false,
 			       virtio_pci__io_mmio_callback, vpci);
 	if (r < 0)
 		goto free_ioport;
@@ -475,8 +474,8 @@ int virtio_pci__init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
 							| PCI_BASE_ADDRESS_SPACE_MEMORY),
 		.status			= cpu_to_le16(PCI_STATUS_CAP_LIST),
 		.capabilities		= (void *)&vpci->pci_hdr.msix - (void *)&vpci->pci_hdr,
-		.bar_size[0]		= cpu_to_le32(IOPORT_SIZE),
-		.bar_size[1]		= cpu_to_le32(IOPORT_SIZE),
+		.bar_size[0]		= cpu_to_le32(PCI_IO_SIZE),
+		.bar_size[1]		= cpu_to_le32(PCI_IO_SIZE),
 		.bar_size[2]		= cpu_to_le32(PCI_IO_SIZE*2),
 	};
 
-- 
2.20.1