On Tue, Jan 31, 2012 at 10:33:14PM -0700, Alex Williamson wrote:
> @@ -1438,11 +1448,71 @@ static void msix_mmio_write(void *opaque,
> target_phys_addr_t addr,
> uint64_t val, unsigned size)
> {
> AssignedDevice *adev = opaque;
> + PCIDevice *pdev = &adev->dev;
> + uint16_t ctrl;
> + MSIXTableEntry orig;
> + int i = addr >> 4;
> +
> + if (i >= adev->msix_max) {
> + return; /* Drop write */
> + }
>
> - DEBUG("write to MSI-X entry table mmio offset 0x%lx, val 0x%lx\n",
> - addr, val);
> + ctrl = pci_get_word(pdev->config + pdev->msix_cap + PCI_MSIX_FLAGS);
> +
> + DEBUG("write to MSI-X table offset 0x%lx, val 0x%lx\n", addr, val);
> +
> + if (ctrl & PCI_MSIX_FLAGS_ENABLE) {
> + orig = adev->msix_table[i];
> + }
>
> memcpy((void *)((uint8_t *)adev->msix_table + addr), &val, size);
Does the core guarantee alignment even if guest violates the rules?
I ask because we validate i above but don't check the low bits
of addr, so a misaligned call can access beyond the array boundary.
If core does not ensure alignment we must check here ourselves.
> +
> + if (ctrl & PCI_MSIX_FLAGS_ENABLE) {
> + MSIXTableEntry *entry = &adev->msix_table[i];
> +
> + if (!msix_masked(&orig) && msix_masked(entry)) {
> + /*
> + * Vector masked, disable it
> + *
> + * XXX It's not clear if we can or should actually attempt
> + * to mask or disable the interrupt. KVM doesn't have
> + * support for pending bits and kvm_assign_set_msix_entry
> + * doesn't modify the device hardware mask. Interrupts
> + * while masked are simply not injected to the guest, so
> + * are lost. Can we get away with always injecting an
> + * interrupt on unmask?
> + */
> + } else if (msix_masked(&orig) && !msix_masked(entry)) {
> + /* Vector unmasked */
> + if (i >= adev->irq_entries_nr || !adev->entry[i].type) {
> + /* Previously unassigned vector, start from scratch */
> + assigned_dev_update_msix(pdev);
> + return;
> + } else {
> + /* Update an existing, previously masked vector */
> + struct kvm_irq_routing_entry orig = adev->entry[i];
> + int ret;
> +
> + adev->entry[i].u.msi.address_lo = entry->addr_lo;
> + adev->entry[i].u.msi.address_hi = entry->addr_hi;
> + adev->entry[i].u.msi.data = entry->data;
> +
> + ret = kvm_update_routing_entry(&orig, &adev->entry[i]);
> + if (ret) {
> + fprintf(stderr,
> + "Error updating irq routing entry (%d)\n", ret);
> + return;
> + }
> +
> + ret = kvm_commit_irq_routes();
> + if (ret) {
> + fprintf(stderr,
> + "Error committing irq routes (%d)\n", ret);
> + return;
> + }
> + }
> + }
> + }
> }
>
> static const MemoryRegionOps msix_mmio_ops = {
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