From fea858dc5d901626e5d794037b5bff9f59b9ded7 Mon Sep 17 00:00:00 2001 From: Nuno Das Neves Date: Thu, 17 Nov 2022 12:11:39 -0800 Subject: [PATCH] iommu/hyper-v: Allow hyperv irq remapping without x2apic If x2apic is not available, hyperv-iommu skips remapping irqs. This breaks root partition which always needs irqs remapped. Fix this by allowing irq remapping regardless of x2apic, and change hyperv_enable_irq_remapping() to return IRQ_REMAP_XAPIC_MODE in case x2apic is missing. Tested with root and non-root hyperv partitions. Signed-off-by: Nuno Das Neves Reviewed-by: Tianyu Lan Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/1668715899-8971-1-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu --- arch/x86/kernel/cpu/mshyperv.c | 6 ++++++ drivers/iommu/Kconfig | 6 +++--- drivers/iommu/hyperv-iommu.c | 11 ++++++++--- 3 files changed, 17 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index 831613959a92..46668e255421 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -475,6 +475,12 @@ static bool __init ms_hyperv_x2apic_available(void) * (logically) generates MSIs directly to the system APIC irq domain. * There is no HPET, and PCI MSI/MSI-X interrupts are remapped by the * pci-hyperv host bridge. + * + * Note: for a Hyper-V root partition, this will always return false. + * The hypervisor doesn't expose these HYPERV_CPUID_VIRT_STACK_* cpuids by + * default, they are implemented as intercepts by the Windows Hyper-V stack. + * Even a nested root partition (L2 root) will not get them because the + * nested (L1) hypervisor filters them out. */ static bool __init ms_hyperv_msi_ext_dest_id(void) { diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig index dc5f7a156ff5..cf7433652db0 100644 --- a/drivers/iommu/Kconfig +++ b/drivers/iommu/Kconfig @@ -474,13 +474,13 @@ config QCOM_IOMMU Support for IOMMU on certain Qualcomm SoCs. config HYPERV_IOMMU - bool "Hyper-V x2APIC IRQ Handling" + bool "Hyper-V IRQ Handling" depends on HYPERV && X86 select IOMMU_API default HYPERV help - Stub IOMMU driver to handle IRQs as to allow Hyper-V Linux - guests to run with x2APIC mode enabled. + Stub IOMMU driver to handle IRQs to support Hyper-V Linux + guest and root partitions. config VIRTIO_IOMMU tristate "Virtio IOMMU driver" diff --git a/drivers/iommu/hyperv-iommu.c b/drivers/iommu/hyperv-iommu.c index e190bb8c225c..8302db7f783e 100644 --- a/drivers/iommu/hyperv-iommu.c +++ b/drivers/iommu/hyperv-iommu.c @@ -122,9 +122,12 @@ static int __init hyperv_prepare_irq_remapping(void) const char *name; const struct irq_domain_ops *ops; + /* + * For a Hyper-V root partition, ms_hyperv_msi_ext_dest_id() + * will always return false. + */ if (!hypervisor_is_type(X86_HYPER_MS_HYPERV) || - x86_init.hyper.msi_ext_dest_id() || - !x2apic_supported()) + x86_init.hyper.msi_ext_dest_id()) return -ENODEV; if (hv_root_partition) { @@ -170,7 +173,9 @@ static int __init hyperv_prepare_irq_remapping(void) static int __init hyperv_enable_irq_remapping(void) { - return IRQ_REMAP_X2APIC_MODE; + if (x2apic_supported()) + return IRQ_REMAP_X2APIC_MODE; + return IRQ_REMAP_XAPIC_MODE; } struct irq_remap_ops hyperv_irq_remap_ops = { -- 2.20.1