On 27/07/2017 2:28, Michael S. Tsirkin wrote:
On Thu, Jul 27, 2017 at 12:54:07AM +0300, Alexander Bezzubikov wrote:
2017-07-26 22:43 GMT+03:00 Michael S. Tsirkin <m...@redhat.com>:
On Sun, Jul 23, 2017 at 01:15:41AM +0300, Aleksandr Bezzubikov wrote:
On PCI init PCI bridges may need some
extra info about bus number to reserve, IO, memory and
prefetchable memory limits. QEMU can provide this
with special
with a special
vendor-specific PCI capability.
Sizes of limits match ones from
PCI Type 1 Configuration Space Header,
number of buses to reserve occupies only 1 byte
since it is the size of Subordinate Bus Number register.
Signed-off-by: Aleksandr Bezzubikov <zuban...@gmail.com>
---
hw/pci/pci_bridge.c | 27 +++++++++++++++++++++++++++
include/hw/pci/pci_bridge.h | 18 ++++++++++++++++++
2 files changed, 45 insertions(+)
diff --git a/hw/pci/pci_bridge.c b/hw/pci/pci_bridge.c
index 720119b..8ec6c2c 100644
--- a/hw/pci/pci_bridge.c
+++ b/hw/pci/pci_bridge.c
@@ -408,6 +408,33 @@ void pci_bridge_map_irq(PCIBridge *br, const char*
bus_name,
br->bus_name = bus_name;
}
+
+int pci_bridge_help_cap_init(PCIDevice *dev, int cap_offset,
help? should be qemu_cap_init?
+ uint8_t bus_reserve, uint32_t io_limit,
+ uint16_t mem_limit, uint64_t pref_limit,
+ Error **errp)
+{
+ size_t cap_len = sizeof(PCIBridgeQemuCap);
+ PCIBridgeQemuCap cap;
This leaks info to guest. You want to init all fields here:
cap = {
.len = ....
};
I surely can do this for len field, but as Laszlo proposed
we can use mutually exclusive fields,
e.g. pref_32 and pref_64, the only way I have left
is to use ternary operator (if we surely need this
big initializer). Keeping some if's would look better,
I think.
+
+ cap.len = cap_len;
+ cap.bus_res = bus_reserve;
+ cap.io_lim = io_limit & 0xFF;
+ cap.io_lim_upper = io_limit >> 8 & 0xFFFF;
+ cap.mem_lim = mem_limit;
+ cap.pref_lim = pref_limit & 0xFFFF;
+ cap.pref_lim_upper = pref_limit >> 16 & 0xFFFFFFFF;
Please use pci_set_word etc or cpu_to_leXX.
Since now we've decided to avoid fields separation into <field> + <field_upper>,
this bitmask along with pci_set_word are no longer needed.
I think it's easiest to replace struct with a set of macros then
pci_set_word does the work for you.
I don't really want to use macros here because structure
show us the whole capability layout and this can
decrease documenting efforts. More than that,
memcpy usage is very convenient here, and I wouldn't like
to lose it.
+
+ int offset = pci_add_capability(dev, PCI_CAP_ID_VNDR,
+ cap_offset, cap_len, errp);
+ if (offset < 0) {
+ return offset;
+ }
+
+ memcpy(dev->config + offset + 2, (char *)&cap + 2, cap_len - 2);
+2 is yacky. See how virtio does it:
memcpy(dev->config + offset + PCI_CAP_FLAGS, &cap->cap_len,
cap->cap_len - PCI_CAP_FLAGS);
OK.
+ return 0;
+}
+
static const TypeInfo pci_bridge_type_info = {
.name = TYPE_PCI_BRIDGE,
.parent = TYPE_PCI_DEVICE,
diff --git a/include/hw/pci/pci_bridge.h b/include/hw/pci/pci_bridge.h
index ff7cbaa..c9f642c 100644
--- a/include/hw/pci/pci_bridge.h
+++ b/include/hw/pci/pci_bridge.h
@@ -67,4 +67,22 @@ void pci_bridge_map_irq(PCIBridge *br, const char* bus_name,
#define PCI_BRIDGE_CTL_DISCARD_STATUS 0x400 /* Discard timer status
*/
#define PCI_BRIDGE_CTL_DISCARD_SERR 0x800 /* Discard timer SERR# enable */
+typedef struct PCIBridgeQemuCap {
+ uint8_t id; /* Standard PCI capability header field */
+ uint8_t next; /* Standard PCI capability header field */
+ uint8_t len; /* Standard PCI vendor-specific capability header field */
+ uint8_t bus_res;
+ uint32_t pref_lim_upper;
Big endian? Ugh.
Agreed, and this's gonna to disappear with
the new layout.
+ uint16_t pref_lim;
+ uint16_t mem_lim;
I'd say we need 64 bit for memory.
Why? Non-prefetchable MEMORY_LIMIT register is 16 bits long.
Hmm ok, but e.g. for io there are bridges that have extra registers
to specify non-standard non-aligned registers.
+ uint16_t io_lim_upper;
+ uint8_t io_lim;
+ uint8_t padding;
IMHO each type should have a special "don't care" flag
that would mean "I don't know".
Don't know what? Now 0 is an indicator to do nothing with this field.
In that case how do you say "don't allocate any memory"?
We can keep the MEM/Limit registers read-only for such cases,
as they are optional registers.
Thanks,
Marcel
+} PCIBridgeQemuCap;
You don't really need this struct in the header. And pls document all fields.
+
+int pci_bridge_help_cap_init(PCIDevice *dev, int cap_offset,
+ uint8_t bus_reserve, uint32_t io_limit,
+ uint16_t mem_limit, uint64_t pref_limit,
+ Error **errp);
+
#endif /* QEMU_PCI_BRIDGE_H */
--
2.7.4
--
Alexander Bezzubikov
