diff options
| author | Jeffrey Hugo <quic_jhugo@quicinc.com> | 2022-04-13 07:36:21 -0600 |
|---|---|---|
| committer | Wei Liu <wei.liu@kernel.org> | 2022-04-25 15:50:17 +0000 |
| commit | 08e61e861a0e47e5e1a3fb78406afd6b0cea6b6d (patch) | |
| tree | e6e617de3ffdf829127729d50c7ef0e37b39e7b2 /drivers/pci/controller/pci-hyperv.c | |
| parent | 66200bbcde697dea7f48071d325ea4dec6f66b11 (diff) | |
PCI: hv: Fix multi-MSI to allow more than one MSI vector
If the allocation of multiple MSI vectors for multi-MSI fails in the core
PCI framework, the framework will retry the allocation as a single MSI
vector, assuming that meets the min_vecs specified by the requesting
driver.
Hyper-V advertises that multi-MSI is supported, but reuses the VECTOR
domain to implement that for x86. The VECTOR domain does not support
multi-MSI, so the alloc will always fail and fallback to a single MSI
allocation.
In short, Hyper-V advertises a capability it does not implement.
Hyper-V can support multi-MSI because it coordinates with the hypervisor
to map the MSIs in the IOMMU's interrupt remapper, which is something the
VECTOR domain does not have. Therefore the fix is simple - copy what the
x86 IOMMU drivers (AMD/Intel-IR) do by removing
X86_IRQ_ALLOC_CONTIGUOUS_VECTORS after calling the VECTOR domain's
pci_msi_prepare().
Fixes: 4daace0d8ce8 ("PCI: hv: Add paravirtual PCI front-end for Microsoft Hyper-V VMs")
Signed-off-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
Link: https://lore.kernel.org/r/1649856981-14649-1-git-send-email-quic_jhugo@quicinc.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Diffstat (limited to 'drivers/pci/controller/pci-hyperv.c')
| -rw-r--r-- | drivers/pci/controller/pci-hyperv.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index d270a204324e..1cbe24b92a38 100644 --- a/drivers/pci/controller/pci-hyperv.c +++ b/drivers/pci/controller/pci-hyperv.c @@ -614,7 +614,16 @@ static void hv_set_msi_entry_from_desc(union hv_msi_entry *msi_entry, static int hv_msi_prepare(struct irq_domain *domain, struct device *dev, int nvec, msi_alloc_info_t *info) { - return pci_msi_prepare(domain, dev, nvec, info); + int ret = pci_msi_prepare(domain, dev, nvec, info); + + /* + * By using the interrupt remapper in the hypervisor IOMMU, contiguous + * CPU vectors is not needed for multi-MSI + */ + if (info->type == X86_IRQ_ALLOC_TYPE_PCI_MSI) + info->flags &= ~X86_IRQ_ALLOC_CONTIGUOUS_VECTORS; + + return ret; } /** |