From: Jeffrey Hugo <quic_jhugo@quicinc.com> stable inclusion from stable-v5.10.134 commit f1d2f1ce05355742f0fdb721e30ddd03de90be94 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5ZVR7 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 08e61e861a0e47e5e1a3fb78406afd6b0cea6b6d upstream. 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(). 5.10 backport - adds the hv_msi_prepare wrapper function 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@quici... Signed-off-by: Wei Liu <wei.liu@kernel.org> Signed-off-by: Carl Vanderlip <quic_carlv@quicinc.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Reviewed-by: Wei Li <liwei391@huawei.com> --- drivers/pci/controller/pci-hyperv.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index a070e69bb49c..84085939769c 100644 --- a/drivers/pci/controller/pci-hyperv.c +++ b/drivers/pci/controller/pci-hyperv.c @@ -1180,6 +1180,21 @@ static void hv_irq_mask(struct irq_data *data) pci_msi_mask_irq(data); } +static int hv_msi_prepare(struct irq_domain *domain, struct device *dev, + int nvec, msi_alloc_info_t *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; +} + /** * hv_irq_unmask() - "Unmask" the IRQ by setting its current * affinity. @@ -1545,7 +1560,7 @@ static struct irq_chip hv_msi_irq_chip = { }; static struct msi_domain_ops hv_msi_ops = { - .msi_prepare = pci_msi_prepare, + .msi_prepare = hv_msi_prepare, .msi_free = hv_msi_free, }; -- 2.20.1