On 04/08/2010 01:52 AM, Cam Macdonell wrote:
Support an inter-vm shared memory device that maps a shared-memory object as a
PCI device in the guest. This patch also supports interrupts between guest by
communicating over a unix domain socket. This patch applies to the qemu-kvm
repository.
-device ivshmem,size=<size in MB>[,shm=<shm name>]
Can that be <size in format accepted by -m> (2M, 4G, 19T, ...).
Interrupts are supported between multiple VMs by using a shared memory server
by using a chardev socket.
-device ivshmem,size=<size in MB>[,shm=<shm name>][,chardev=<id>][,msi=on]
[,irqfd=on][,vectors=n]
-chardev socket,path=<path>,id=<id>
Do we need the irqfd parameter? Should be on by default.
On the other hand, it may fail with older kernels with limited irqfd
slots, so better keep it there.
Sample programs, init scripts and the shared memory server are available in a
git repo here:
www.gitorious.org/nahanni
Please consider qemu.git/contrib.
---
Makefile.target | 3 +
hw/ivshmem.c | 700 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
qemu-char.c | 6 +
qemu-char.h | 3 +
qemu-doc.texi | 45 +++++++++++++
4 files changed, 712 insertions(+), 0 deletions(-)
create mode 100644 hw/ivshmem.c
diff --git a/Makefile.target b/Makefile.target
index 1ffd802..bc9a681 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -199,6 +199,9 @@ obj-$(CONFIG_USB_OHCI) += usb-ohci.o
obj-y += rtl8139.o
obj-y += e1000.o
+# Inter-VM PCI shared memory
+obj-y += ivshmem.o
+
depends on CONFIG_PCI
# Hardware support
+
+#define PCI_COMMAND_IOACCESS 0x0001
+#define PCI_COMMAND_MEMACCESS 0x0002
Should be in pci.h?
+
+#define DEBUG_IVSHMEM
Disable for production.
+
+#define IVSHMEM_IRQFD 0
+#define IVSHMEM_MSI 1
+#define IVSHMEM_MAX_EVENTFDS 16
Too low? why limit?
+
+struct eventfd_entry {
+ PCIDevice *pdev;
+ int vector;
+};
Coding style: EventfdEntry, and a typedef.
+
+typedef struct IVShmemState {
+ PCIDevice dev;
+ uint32_t intrmask;
+ uint32_t intrstatus;
+ uint32_t doorbell;
+
+ CharDriverState * chr;
+ CharDriverState ** eventfd_chr;
+ int ivshmem_mmio_io_addr;
+
+ pcibus_t mmio_addr;
+ uint8_t *ivshmem_ptr;
+ unsigned long ivshmem_offset;
off_t
+ unsigned int ivshmem_size;
ram_addr_t
+
+/* accessing registers - based on rtl8139 */
+static void ivshmem_update_irq(IVShmemState *s, int val)
+{
+ int isr;
+ isr = (s->intrstatus& s->intrmask)& 0xffffffff;
This is highly undocumented, but fits my suggested 'status is bitmap'.
'isr' needs to be uint32_t if you mask it like that.
+
+ /* don't print ISR resets */
+ if (isr) {
+ IVSHMEM_DPRINTF("Set IRQ to %d (%04x %04x)\n",
+ isr ? 1 : 0, s->intrstatus, s->intrmask);
+ }
+
+ qemu_set_irq(s->dev.irq[0], (isr != 0));
+}
+
+
+
+static void create_shared_memory_BAR(IVShmemState *s, int fd) {
+
+ s->shm_fd = fd;
+
+ s->ivshmem_offset = qemu_ram_mmap(s->shm_fd, s->ivshmem_size,
+ MAP_SHARED, 0);
Where did the offset go?
+
+ s->ivshmem_ptr = qemu_get_ram_ptr(s->ivshmem_offset);
Never used, please drop.
+
+ /* region for shared memory */
+ pci_register_bar(&s->dev, 2, s->ivshmem_size,
+ PCI_BASE_ADDRESS_SPACE_MEMORY, ivshmem_map);
Might be worthwhile to mark it as a 64-bit BAR. Please test with
ridiculous shared memory sizes.
+}
+
+static int ivshmem_irqfd(PCIDevice* pdev, uint16_t vector, int fd)
+{
+ struct kvm_irqfd call = { };
+ int r;
+
+ IVSHMEM_DPRINTF("inside irqfd\n");
+ if (vector>= pdev->msix_entries_nr)
+ return -EINVAL;
+ call.fd = fd;
+ call.gsi = pdev->msix_irq_entries[vector].gsi;
+ r = kvm_vm_ioctl(kvm_state, KVM_IRQFD,&call);
+ if (r< 0) {
+ IVSHMEM_DPRINTF("allocating irqfd failed %d\n", r);
+ return r;
+ }
+ return 0;
+}
should be in kvm.c for reuse.
+
+static int ivshmem_ioeventfd(IVShmemState* s, int posn, int fd, int vector)
+{
+
+ int ret;
+ struct kvm_ioeventfd iofd;
+
+ iofd.datamatch = (posn<< 16) | vector;
+ iofd.addr = s->mmio_addr + Doorbell;
+ iofd.len = 4;
+ iofd.flags = KVM_IOEVENTFD_FLAG_DATAMATCH;
+ iofd.fd = fd;
+
+ ret = kvm_vm_ioctl(kvm_state, KVM_IOEVENTFD,&iofd);
Ditto.
+
+ if (ret< 0) {
+ fprintf(stderr, "error assigning ioeventfd (%d)\n", ret);
+ perror(strerror(ret));
+ } else {
+ IVSHMEM_DPRINTF("success assigning ioeventfd (%d:%d)\n", posn, vector);
+ }
+
+ return ret;
+}
blank line here.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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