From feb9a2ab4b0260d8d680a7ffd25063dafc7ec628 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Sun, 6 Jan 2013 21:30:31 -0700 Subject: pci-assign: Enable MSIX on device to match guest When a guest enables MSIX on a device we evaluate the MSIX vector table, typically find no unmasked vectors and don't switch the device to MSIX mode. This generally works fine and the device will be switched once the guest enables and therefore unmasks a vector. Unfortunately some drivers enable MSIX, then use interfaces to send commands between VF & PF or PF & firmware that act based on the host state of the device. These therefore may break when MSIX is managed lazily. This change re-enables the previous test used to enable MSIX (see qemu-kvm a6b402c9), which basically guesses whether a vector will be used based on the data field of the vector table. Cc: qemu-stable@nongnu.org Signed-off-by: Alex Williamson Acked-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/kvm/pci-assign.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/hw/kvm/pci-assign.c b/hw/kvm/pci-assign.c index 8ee94287ff..896cfe8a59 100644 --- a/hw/kvm/pci-assign.c +++ b/hw/kvm/pci-assign.c @@ -1031,6 +1031,19 @@ static bool assigned_dev_msix_masked(MSIXTableEntry *entry) return (entry->ctrl & cpu_to_le32(0x1)) != 0; } +/* + * When MSI-X is first enabled the vector table typically has all the + * vectors masked, so we can't use that as the obvious test to figure out + * how many vectors to initially enable. Instead we look at the data field + * because this is what worked for pci-assign for a long time. This makes + * sure the physical MSI-X state tracks the guest's view, which is important + * for some VF/PF and PF/fw communication channels. + */ +static bool assigned_dev_msix_skipped(MSIXTableEntry *entry) +{ + return !entry->data; +} + static int assigned_dev_update_msix_mmio(PCIDevice *pci_dev) { AssignedDevice *adev = DO_UPCAST(AssignedDevice, dev, pci_dev); @@ -1041,7 +1054,7 @@ static int assigned_dev_update_msix_mmio(PCIDevice *pci_dev) /* Get the usable entry number for allocating */ for (i = 0; i < adev->msix_max; i++, entry++) { - if (assigned_dev_msix_masked(entry)) { + if (assigned_dev_msix_skipped(entry)) { continue; } entries_nr++; @@ -1070,7 +1083,7 @@ static int assigned_dev_update_msix_mmio(PCIDevice *pci_dev) for (i = 0; i < adev->msix_max; i++, entry++) { adev->msi_virq[i] = -1; - if (assigned_dev_msix_masked(entry)) { + if (assigned_dev_msix_skipped(entry)) { continue; } -- cgit v1.2.1