Merge tag 'hyperv-next-signed-20221208' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux

Pull hyperv updates from Wei Liu:

 - Drop unregister syscore from hyperv_cleanup to avoid hang (Gaurav
   Kohli)

 - Clean up panic path for Hyper-V framebuffer (Guilherme G. Piccoli)

 - Allow IRQ remapping to work without x2apic (Nuno Das Neves)

 - Fix comments (Olaf Hering)

 - Expand hv_vp_assist_page definition (Saurabh Sengar)

 - Improvement to page reporting (Shradha Gupta)

 - Make sure TSC clocksource works when Linux runs as the root partition
   (Stanislav Kinsburskiy)

* tag 'hyperv-next-signed-20221208' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux:
  x86/hyperv: Remove unregister syscore call from Hyper-V cleanup
  iommu/hyper-v: Allow hyperv irq remapping without x2apic
  clocksource: hyper-v: Add TSC page support for root partition
  clocksource: hyper-v: Use TSC PFN getter to map vvar page
  clocksource: hyper-v: Introduce TSC PFN getter
  clocksource: hyper-v: Introduce a pointer to TSC page
  x86/hyperv: Expand definition of struct hv_vp_assist_page
  PCI: hv: update comment in x86 specific hv_arch_irq_unmask
  hv: fix comment typo in vmbus_channel/low_latency
  drivers: hv, hyperv_fb: Untangle and refactor Hyper-V panic notifiers
  video: hyperv_fb: Avoid taking busy spinlock on panic path
  hv_balloon: Add support for configurable order free page reporting
  mm/page_reporting: Add checks for page_reporting_order param

2 files changed, 11 insertions, 6 deletions

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 = {