Merge tag 'hyperv-fixes-signed-20250718' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux

Pull hyperv fixes from Wei Liu:

 - Select use CONFIG_SYSFB only if EFI is enabled (Michael Kelley)

 - An assorted set of fixes to remove warnings for missing export.h
   header inclusion (Naman Jain)

 - An assorted set of fixes for when Linux run as the root partition
   for Microsoft Hypervisor (Mukesh Rathor, Nuno Das Neves, Stanislav
   Kinsburskii)

 - Fix the check for HYPERVISOR_CALLBACK_VECTOR (Naman Jain)

 - Fix fcopy tool to handle irregularities with size of ring buffer
   (Naman Jain)

 - Fix incorrect file path conversion in fcopy tool (Yasumasa Suenaga)

* tag 'hyperv-fixes-signed-20250718' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux:
  tools/hv: fcopy: Fix irregularities with size of ring buffer
  PCI: hv: Use the correct hypercall for unmasking interrupts on nested
  x86/hyperv: Expose hv_map_msi_interrupt()
  Drivers: hv: Use nested hypercall for post message and signal event
  x86/hyperv: Clean up hv_map/unmap_interrupt() return values
  x86/hyperv: Fix usage of cpu_online_mask to get valid cpu
  PCI: hv: Don't load the driver for baremetal root partition
  net: mana: Fix warnings for missing export.h header inclusion
  PCI: hv: Fix warnings for missing export.h header inclusion
  clocksource: hyper-v: Fix warnings for missing export.h header inclusion
  x86/hyperv: Fix warnings for missing export.h header inclusion
  Drivers: hv: Fix warnings for missing export.h header inclusion
  Drivers: hv: Fix the check for HYPERVISOR_CALLBACK_VECTOR
  tools/hv: fcopy: Fix incorrect file path conversion
  Drivers: hv: Select CONFIG_SYSFB only if EFI is enabled

22 files changed, 196 insertions, 112 deletions

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 3d1d3547095a..afdbda2dd7b7 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -34,6 +34,7 @@
 #include <linux/syscore_ops.h>
 #include <clocksource/hyperv_timer.h>
 #include <linux/highmem.h>
+#include <linux/export.h>
 
 void *hv_hypercall_pg;
 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
diff --git a/arch/x86/hyperv/irqdomain.c b/arch/x86/hyperv/irqdomain.c
index 31f0d29cbc5e..090f5ac9f492 100644
--- a/arch/x86/hyperv/irqdomain.c
+++ b/arch/x86/hyperv/irqdomain.c
@@ -10,6 +10,7 @@
 
 #include <linux/pci.h>
 #include <linux/irq.h>
+#include <linux/export.h>
 #include <asm/mshyperv.h>
 
 static int hv_map_interrupt(union hv_device_id device_id, bool level,
@@ -46,7 +47,7 @@ static int hv_map_interrupt(union hv_device_id device_id, bool level,
 	if (nr_bank < 0) {
 		local_irq_restore(flags);
 		pr_err("%s: unable to generate VP set\n", __func__);
-		return EINVAL;
+		return -EINVAL;
 	}
 	intr_desc->target.flags = HV_DEVICE_INTERRUPT_TARGET_PROCESSOR_SET;
 
@@ -66,7 +67,7 @@ static int hv_map_interrupt(union hv_device_id device_id, bool level,
 	if (!hv_result_success(status))
 		hv_status_err(status, "\n");
 
-	return hv_result(status);
+	return hv_result_to_errno(status);
 }
 
 static int hv_unmap_interrupt(u64 id, struct hv_interrupt_entry *old_entry)
@@ -88,7 +89,10 @@ static int hv_unmap_interrupt(u64 id, struct hv_interrupt_entry *old_entry)
 	status = hv_do_hypercall(HVCALL_UNMAP_DEVICE_INTERRUPT, input, NULL);
 	local_irq_restore(flags);
 
-	return hv_result(status);
+	if (!hv_result_success(status))
+		hv_status_err(status, "\n");
+
+	return hv_result_to_errno(status);
 }
 
 #ifdef CONFIG_PCI_MSI
@@ -169,13 +173,34 @@ static union hv_device_id hv_build_pci_dev_id(struct pci_dev *dev)
 	return dev_id;
 }
 
-static int hv_map_msi_interrupt(struct pci_dev *dev, int cpu, int vector,
-				struct hv_interrupt_entry *entry)
+/**
+ * hv_map_msi_interrupt() - "Map" the MSI IRQ in the hypervisor.
+ * @data:      Describes the IRQ
+ * @out_entry: Hypervisor (MSI) interrupt entry (can be NULL)
+ *
+ * Map the IRQ in the hypervisor by issuing a MAP_DEVICE_INTERRUPT hypercall.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int hv_map_msi_interrupt(struct irq_data *data,
+			 struct hv_interrupt_entry *out_entry)
 {
-	union hv_device_id device_id = hv_build_pci_dev_id(dev);
+	struct irq_cfg *cfg = irqd_cfg(data);
+	struct hv_interrupt_entry dummy;
+	union hv_device_id device_id;
+	struct msi_desc *msidesc;
+	struct pci_dev *dev;
+	int cpu;
 
-	return hv_map_interrupt(device_id, false, cpu, vector, entry);
+	msidesc = irq_data_get_msi_desc(data);
+	dev = msi_desc_to_pci_dev(msidesc);
+	device_id = hv_build_pci_dev_id(dev);
+	cpu = cpumask_first(irq_data_get_effective_affinity_mask(data));
+
+	return hv_map_interrupt(device_id, false, cpu, cfg->vector,
+				out_entry ? out_entry : &dummy);
 }
+EXPORT_SYMBOL_GPL(hv_map_msi_interrupt);
 
 static inline void entry_to_msi_msg(struct hv_interrupt_entry *entry, struct msi_msg *msg)
 {
@@ -188,13 +213,11 @@ static inline void entry_to_msi_msg(struct hv_interrupt_entry *entry, struct msi
 static int hv_unmap_msi_interrupt(struct pci_dev *dev, struct hv_interrupt_entry *old_entry);
 static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
 {
+	struct hv_interrupt_entry *stored_entry;
+	struct irq_cfg *cfg = irqd_cfg(data);
 	struct msi_desc *msidesc;
 	struct pci_dev *dev;
-	struct hv_interrupt_entry out_entry, *stored_entry;
-	struct irq_cfg *cfg = irqd_cfg(data);
-	const cpumask_t *affinity;
-	int cpu;
-	u64 status;
+	int ret;
 
 	msidesc = irq_data_get_msi_desc(data);
 	dev = msi_desc_to_pci_dev(msidesc);
@@ -204,9 +227,6 @@ static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
 		return;
 	}
 
-	affinity = irq_data_get_effective_affinity_mask(data);
-	cpu = cpumask_first_and(affinity, cpu_online_mask);
-
 	if (data->chip_data) {
 		/*
 		 * This interrupt is already mapped. Let's unmap first.
@@ -219,14 +239,12 @@ static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
 		stored_entry = data->chip_data;
 		data->chip_data = NULL;
 
-		status = hv_unmap_msi_interrupt(dev, stored_entry);
+		ret = hv_unmap_msi_interrupt(dev, stored_entry);
 
 		kfree(stored_entry);
 
-		if (status != HV_STATUS_SUCCESS) {
-			hv_status_debug(status, "failed to unmap\n");
+		if (ret)
 			return;
-		}
 	}
 
 	stored_entry = kzalloc(sizeof(*stored_entry), GFP_ATOMIC);
@@ -235,15 +253,14 @@ static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
 		return;
 	}
 
-	status = hv_map_msi_interrupt(dev, cpu, cfg->vector, &out_entry);
-	if (status != HV_STATUS_SUCCESS) {
+	ret = hv_map_msi_interrupt(data, stored_entry);
+	if (ret) {
 		kfree(stored_entry);
 		return;
 	}
 
-	*stored_entry = out_entry;
 	data->chip_data = stored_entry;
-	entry_to_msi_msg(&out_entry, msg);
+	entry_to_msi_msg(data->chip_data, msg);
 
 	return;
 }
@@ -257,7 +274,6 @@ static void hv_teardown_msi_irq(struct pci_dev *dev, struct irq_data *irqd)
 {
 	struct hv_interrupt_entry old_entry;
 	struct msi_msg msg;
-	u64 status;
 
 	if (!irqd->chip_data) {
 		pr_debug("%s: no chip data\n!", __func__);
@@ -270,10 +286,7 @@ static void hv_teardown_msi_irq(struct pci_dev *dev, struct irq_data *irqd)
 	kfree(irqd->chip_data);
 	irqd->chip_data = NULL;
 
-	status = hv_unmap_msi_interrupt(dev, &old_entry);
-
-	if (status != HV_STATUS_SUCCESS)
-		hv_status_err(status, "\n");
+	(void)hv_unmap_msi_interrupt(dev, &old_entry);
 }
 
 static void hv_msi_free_irq(struct irq_domain *domain,
diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index e93a2f488ff7..ade6c665c97e 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -10,6 +10,7 @@
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/cpu.h>
+#include <linux/export.h>
 #include <asm/svm.h>
 #include <asm/sev.h>
 #include <asm/io.h>
diff --git a/arch/x86/hyperv/nested.c b/arch/x86/hyperv/nested.c
index 1083dc8646f9..8ccbb7c4fc27 100644
--- a/arch/x86/hyperv/nested.c
+++ b/arch/x86/hyperv/nested.c
@@ -11,6 +11,7 @@
 
 
 #include <linux/types.h>
+#include <linux/export.h>
 #include <hyperv/hvhdk.h>
 #include <asm/mshyperv.h>
 #include <asm/tlbflush.h>
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index e1752ba47e67..abc4659f5809 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -112,12 +112,6 @@ static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
 	return hv_status;
 }
 
-/* Hypercall to the L0 hypervisor */
-static inline u64 hv_do_nested_hypercall(u64 control, void *input, void *output)
-{
-	return hv_do_hypercall(control | HV_HYPERCALL_NESTED, input, output);
-}
-
 /* Fast hypercall with 8 bytes of input and no output */
 static inline u64 _hv_do_fast_hypercall8(u64 control, u64 input1)
 {
@@ -165,13 +159,6 @@ static inline u64 hv_do_fast_hypercall8(u16 code, u64 input1)
 	return _hv_do_fast_hypercall8(control, input1);
 }
 
-static inline u64 hv_do_fast_nested_hypercall8(u16 code, u64 input1)
-{
-	u64 control = (u64)code | HV_HYPERCALL_FAST_BIT | HV_HYPERCALL_NESTED;
-
-	return _hv_do_fast_hypercall8(control, input1);
-}
-
 /* Fast hypercall with 16 bytes of input */
 static inline u64 _hv_do_fast_hypercall16(u64 control, u64 input1, u64 input2)
 {
@@ -223,13 +210,6 @@ static inline u64 hv_do_fast_hypercall16(u16 code, u64 input1, u64 input2)
 	return _hv_do_fast_hypercall16(control, input1, input2);
 }
 
-static inline u64 hv_do_fast_nested_hypercall16(u16 code, u64 input1, u64 input2)
-{
-	u64 control = (u64)code | HV_HYPERCALL_FAST_BIT | HV_HYPERCALL_NESTED;
-
-	return _hv_do_fast_hypercall16(control, input1, input2);
-}
-
 extern struct hv_vp_assist_page **hv_vp_assist_page;
 
 static inline struct hv_vp_assist_page *hv_get_vp_assist_page(unsigned int cpu)
@@ -262,6 +242,8 @@ static inline void hv_apic_init(void) {}
 
 struct irq_domain *hv_create_pci_msi_domain(void);
 
+int hv_map_msi_interrupt(struct irq_data *data,
+			 struct hv_interrupt_entry *out_entry);
 int hv_map_ioapic_interrupt(int ioapic_id, bool level, int vcpu, int vector,
 		struct hv_interrupt_entry *entry);
 int hv_unmap_ioapic_interrupt(int ioapic_id, struct hv_interrupt_entry *entry);
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index 09549451dd51..2edc13ca184e 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -22,6 +22,7 @@
 #include <linux/irq.h>
 #include <linux/acpi.h>
 #include <linux/hyperv.h>
+#include <linux/export.h>
 #include <clocksource/hyperv_timer.h>
 #include <hyperv/hvhdk.h>
 #include <asm/mshyperv.h>
diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
index 1cd188b73b74..57623ca7f350 100644
--- a/drivers/hv/Kconfig
+++ b/drivers/hv/Kconfig
@@ -9,7 +9,7 @@ config HYPERV
 	select PARAVIRT
 	select X86_HV_CALLBACK_VECTOR if X86
 	select OF_EARLY_FLATTREE if OF
-	select SYSFB if !HYPERV_VTL_MODE
+	select SYSFB if EFI && !HYPERV_VTL_MODE
 	help
 	  Select this option to run Linux as a Hyper-V client operating
 	  system.
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 35f26fa1ffe7..7c7c66e0dc3f 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -18,6 +18,7 @@
 #include <linux/uio.h>
 #include <linux/interrupt.h>
 #include <linux/set_memory.h>
+#include <linux/export.h>
 #include <asm/page.h>
 #include <asm/mshyperv.h>
 
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 6e084c207414..65dd299e2944 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -20,6 +20,7 @@
 #include <linux/delay.h>
 #include <linux/cpu.h>
 #include <linux/hyperv.h>
+#include <linux/export.h>
 #include <asm/mshyperv.h>
 #include <linux/sched/isolation.h>
 
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index be490c598785..1fe3573ae52a 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -519,7 +519,10 @@ void vmbus_set_event(struct vmbus_channel *channel)
 		else
 			WARN_ON_ONCE(1);
 	} else {
-		hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
+		u64 control = HVCALL_SIGNAL_EVENT;
+
+		control |= hv_nested ? HV_HYPERCALL_NESTED : 0;
+		hv_do_fast_hypercall8(control, channel->sig_event);
 	}
 }
 EXPORT_SYMBOL_GPL(vmbus_set_event);
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 308c8f279df8..b14c5f9e0ef2 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -85,8 +85,10 @@ int hv_post_message(union hv_connection_id connection_id,
 		else
 			status = HV_STATUS_INVALID_PARAMETER;
 	} else {
-		status = hv_do_hypercall(HVCALL_POST_MESSAGE,
-					 aligned_msg, NULL);
+		u64 control = HVCALL_POST_MESSAGE;
+
+		control |= hv_nested ? HV_HYPERCALL_NESTED : 0;
+		status = hv_do_hypercall(control, aligned_msg, NULL);
 	}
 
 	local_irq_restore(flags);
diff --git a/drivers/hv/hv_proc.c b/drivers/hv/hv_proc.c
index 7d7ecb6f6137..fbb4eb3901bb 100644
--- a/drivers/hv/hv_proc.c
+++ b/drivers/hv/hv_proc.c
@@ -6,6 +6,7 @@
 #include <linux/slab.h>
 #include <linux/cpuhotplug.h>
 #include <linux/minmax.h>
+#include <linux/export.h>
 #include <asm/mshyperv.h>
 
 /*
diff --git a/drivers/hv/mshv_common.c b/drivers/hv/mshv_common.c
index 2575e6d7a71f..6f227a8a5af7 100644
--- a/drivers/hv/mshv_common.c
+++ b/drivers/hv/mshv_common.c
@@ -13,6 +13,7 @@
 #include <linux/mm.h>
 #include <asm/mshyperv.h>
 #include <linux/resume_user_mode.h>
+#include <linux/export.h>
 
 #include "mshv.h"
 
diff --git a/drivers/hv/mshv_root_hv_call.c b/drivers/hv/mshv_root_hv_call.c
index a222a16107f6..c9c274f29c3c 100644
--- a/drivers/hv/mshv_root_hv_call.c
+++ b/drivers/hv/mshv_root_hv_call.c
@@ -9,6 +9,7 @@
 
 #include <linux/kernel.h>
 #include <linux/mm.h>
+#include <linux/export.h>
 #include <asm/mshyperv.h>
 
 #include "mshv_root.h"
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 3c9b02471760..23ce1fb70de1 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -18,6 +18,7 @@
 #include <linux/slab.h>
 #include <linux/prefetch.h>
 #include <linux/io.h>
+#include <linux/export.h>
 #include <asm/mshyperv.h>
 
 #include "hyperv_vmbus.h"
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 33b524b4eb5e..2ed5a1e89d69 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -2509,7 +2509,7 @@ static int vmbus_acpi_add(struct platform_device *pdev)
 	return 0;
 }
 #endif
-
+#ifndef HYPERVISOR_CALLBACK_VECTOR
 static int vmbus_set_irq(struct platform_device *pdev)
 {
 	struct irq_data *data;
@@ -2534,6 +2534,7 @@ static int vmbus_set_irq(struct platform_device *pdev)
 
 	return 0;
 }
+#endif
 
 static int vmbus_device_add(struct platform_device *pdev)
 {
@@ -2549,11 +2550,11 @@ static int vmbus_device_add(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	if (!__is_defined(HYPERVISOR_CALLBACK_VECTOR))
-		ret = vmbus_set_irq(pdev);
+#ifndef HYPERVISOR_CALLBACK_VECTOR
+	ret = vmbus_set_irq(pdev);
 	if (ret)
 		return ret;
-
+#endif
 	for_each_of_range(&parser, &range) {
 		struct resource *res;
 
diff --git a/drivers/iommu/hyperv-iommu.c b/drivers/iommu/hyperv-iommu.c
index 761ab647f372..0961ac805944 100644
--- a/drivers/iommu/hyperv-iommu.c
+++ b/drivers/iommu/hyperv-iommu.c
@@ -193,15 +193,13 @@ struct hyperv_root_ir_data {
 static void
 hyperv_root_ir_compose_msi_msg(struct irq_data *irq_data, struct msi_msg *msg)
 {
-	u64 status;
-	u32 vector;
-	struct irq_cfg *cfg;
-	int ioapic_id;
-	const struct cpumask *affinity;
-	int cpu;
-	struct hv_interrupt_entry entry;
 	struct hyperv_root_ir_data *data = irq_data->chip_data;
+	struct hv_interrupt_entry entry;
+	const struct cpumask *affinity;
 	struct IO_APIC_route_entry e;
+	struct irq_cfg *cfg;
+	int cpu, ioapic_id;
+	u32 vector;
 
 	cfg = irqd_cfg(irq_data);
 	affinity = irq_data_get_effective_affinity_mask(irq_data);
@@ -214,23 +212,16 @@ hyperv_root_ir_compose_msi_msg(struct irq_data *irq_data, struct msi_msg *msg)
 	    && data->entry.ioapic_rte.as_uint64) {
 		entry = data->entry;
 
-		status = hv_unmap_ioapic_interrupt(ioapic_id, &entry);
-
-		if (status != HV_STATUS_SUCCESS)
-			hv_status_debug(status, "failed to unmap\n");
+		(void)hv_unmap_ioapic_interrupt(ioapic_id, &entry);
 
 		data->entry.ioapic_rte.as_uint64 = 0;
 		data->entry.source = 0; /* Invalid source */
 	}
 
 
-	status = hv_map_ioapic_interrupt(ioapic_id, data->is_level, cpu,
-					vector, &entry);
-
-	if (status != HV_STATUS_SUCCESS) {
-		hv_status_err(status, "map failed\n");
+	if (hv_map_ioapic_interrupt(ioapic_id, data->is_level, cpu,
+				    vector, &entry))
 		return;
-	}
 
 	data->entry = entry;
 
@@ -322,10 +313,10 @@ static void hyperv_root_irq_remapping_free(struct irq_domain *domain,
 			data = irq_data->chip_data;
 			e = &data->entry;
 
-			if (e->source == HV_DEVICE_TYPE_IOAPIC
-			      && e->ioapic_rte.as_uint64)
-				hv_unmap_ioapic_interrupt(data->ioapic_id,
-							&data->entry);
+			if (e->source == HV_DEVICE_TYPE_IOAPIC &&
+			    e->ioapic_rte.as_uint64)
+				(void)hv_unmap_ioapic_interrupt(data->ioapic_id,
+								&data->entry);
 
 			kfree(data);
 		}
diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c b/drivers/net/ethernet/microsoft/mana/gdma_main.c
index 52cf7112762c..58f8ee710912 100644
--- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
+++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
@@ -6,6 +6,7 @@
 #include <linux/pci.h>
 #include <linux/utsname.h>
 #include <linux/version.h>
+#include <linux/export.h>
 
 #include <net/mana/mana.h>
 
diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
index ccd2885c939e..faad1cb880f8 100644
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
@@ -10,6 +10,7 @@
 #include <linux/filter.h>
 #include <linux/mm.h>
 #include <linux/pci.h>
+#include <linux/export.h>
 
 #include <net/checksum.h>
 #include <net/ip6_checksum.h>
diff --git a/drivers/pci/controller/pci-hyperv-intf.c b/drivers/pci/controller/pci-hyperv-intf.c
index cc96be450360..28b3e93d31c0 100644
--- a/drivers/pci/controller/pci-hyperv-intf.c
+++ b/drivers/pci/controller/pci-hyperv-intf.c
@@ -14,6 +14,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/hyperv.h>
+#include <linux/export.h>
 
 struct hyperv_pci_block_ops hvpci_block_ops;
 EXPORT_SYMBOL_GPL(hvpci_block_ops);
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index ef5d655a0052..13680363ff19 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -600,7 +600,7 @@ static unsigned int hv_msi_get_int_vector(struct irq_data *data)
 #define hv_msi_prepare		pci_msi_prepare
 
 /**
- * hv_arch_irq_unmask() - "Unmask" the IRQ by setting its current
+ * hv_irq_retarget_interrupt() - "Unmask" the IRQ by setting its current
  * affinity.
  * @data:	Describes the IRQ
  *
@@ -609,7 +609,7 @@ static unsigned int hv_msi_get_int_vector(struct irq_data *data)
  * is built out of this PCI bus's instance GUID and the function
  * number of the device.
  */
-static void hv_arch_irq_unmask(struct irq_data *data)
+static void hv_irq_retarget_interrupt(struct irq_data *data)
 {
 	struct msi_desc *msi_desc = irq_data_get_msi_desc(data);
 	struct hv_retarget_device_interrupt *params;
@@ -714,6 +714,20 @@ out:
 		dev_err(&hbus->hdev->device,
 			"%s() failed: %#llx", __func__, res);
 }
+
+static void hv_arch_irq_unmask(struct irq_data *data)
+{
+	if (hv_root_partition())
+		/*
+		 * In case of the nested root partition, the nested hypervisor
+		 * is taking care of interrupt remapping and thus the
+		 * MAP_DEVICE_INTERRUPT hypercall is required instead of
+		 * RETARGET_INTERRUPT.
+		 */
+		(void)hv_map_msi_interrupt(data, NULL);
+	else
+		hv_irq_retarget_interrupt(data);
+}
 #elif defined(CONFIG_ARM64)
 /*
  * SPI vectors to use for vPCI; arch SPIs range is [32, 1019], but leaving a bit
@@ -4144,6 +4158,9 @@ static int __init init_hv_pci_drv(void)
 	if (!hv_is_hyperv_initialized())
 		return -ENODEV;
 
+	if (hv_root_partition() && !hv_nested)
+		return -ENODEV;
+
 	ret = hv_pci_irqchip_init();
 	if (ret)
 		return ret;
diff --git a/tools/hv/hv_fcopy_uio_daemon.c b/tools/hv/hv_fcopy_uio_daemon.c
index 0198321d14a2..92e8307b2a46 100644
--- a/tools/hv/hv_fcopy_uio_daemon.c
+++ b/tools/hv/hv_fcopy_uio_daemon.c
@@ -35,7 +35,10 @@
 #define WIN8_SRV_MINOR		1
 #define WIN8_SRV_VERSION	(WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR)
 
-#define FCOPY_UIO		"/sys/bus/vmbus/devices/eb765408-105f-49b6-b4aa-c123b64d17d4/uio"
+#define FCOPY_DEVICE_PATH(subdir) \
+	"/sys/bus/vmbus/devices/eb765408-105f-49b6-b4aa-c123b64d17d4/" #subdir
+#define FCOPY_UIO_PATH          FCOPY_DEVICE_PATH(uio)
+#define FCOPY_CHANNELS_PATH     FCOPY_DEVICE_PATH(channels)
 
 #define FCOPY_VER_COUNT		1
 static const int fcopy_versions[] = {
@@ -47,9 +50,62 @@ static const int fw_versions[] = {
 	UTIL_FW_VERSION
 };
 
-#define HV_RING_SIZE		0x4000 /* 16KB ring buffer size */
+static uint32_t get_ring_buffer_size(void)
+{
+	char ring_path[PATH_MAX];
+	DIR *dir;
+	struct dirent *entry;
+	struct stat st;
+	uint32_t ring_size = 0;
+	int retry_count = 0;
+
+	/* Find the channel directory */
+	dir = opendir(FCOPY_CHANNELS_PATH);
+	if (!dir) {
+		usleep(100 * 1000); /* Avoid race with kernel, wait 100ms and retry once */
+		dir = opendir(FCOPY_CHANNELS_PATH);
+		if (!dir) {
+			syslog(LOG_ERR, "Failed to open channels directory: %s", strerror(errno));
+			return 0;
+		}
+	}
+
+retry_once:
+	while ((entry = readdir(dir)) != NULL) {
+		if (entry->d_type == DT_DIR && strcmp(entry->d_name, ".") != 0 &&
+		    strcmp(entry->d_name, "..") != 0) {
+			snprintf(ring_path, sizeof(ring_path), "%s/%s/ring",
+				 FCOPY_CHANNELS_PATH, entry->d_name);
+
+			if (stat(ring_path, &st) == 0) {
+				/*
+				 * stat returns size of Tx, Rx rings combined,
+				 * so take half of it for individual ring size.
+				 */
+				ring_size = (uint32_t)st.st_size / 2;
+				syslog(LOG_INFO, "Ring buffer size from %s: %u bytes",
+				       ring_path, ring_size);
+				break;
+			}
+		}
+	}
+
+	if (!ring_size && retry_count == 0) {
+		retry_count = 1;
+		rewinddir(dir);
+		usleep(100 * 1000); /* Wait 100ms and retry once */
+		goto retry_once;
+	}
+
+	closedir(dir);
 
-static unsigned char desc[HV_RING_SIZE];
+	if (!ring_size)
+		syslog(LOG_ERR, "Could not determine ring size");
+
+	return ring_size;
+}
+
+static unsigned char *desc;
 
 static int target_fd;
 static char target_fname[PATH_MAX];
@@ -62,8 +118,11 @@ static int hv_fcopy_create_file(char *file_name, char *path_name, __u32 flags)
 
 	filesize = 0;
 	p = path_name;
-	snprintf(target_fname, sizeof(target_fname), "%s/%s",
-		 path_name, file_name);
+	if (snprintf(target_fname, sizeof(target_fname), "%s/%s",
+		     path_name, file_name) >= sizeof(target_fname)) {
+		syslog(LOG_ERR, "target file name is too long: %s/%s", path_name, file_name);
+		goto done;
+	}
 
 	/*
 	 * Check to see if the path is already in place; if not,
@@ -270,7 +329,7 @@ static void wcstoutf8(char *dest, const __u16 *src, size_t dest_size)
 {
 	size_t len = 0;
 
-	while (len < dest_size) {
+	while (len < dest_size && *src) {
 		if (src[len] < 0x80)
 			dest[len++] = (char)(*src++);
 		else
@@ -282,27 +341,15 @@ static void wcstoutf8(char *dest, const __u16 *src, size_t dest_size)
 
 static int hv_fcopy_start(struct hv_start_fcopy *smsg_in)
 {
-	setlocale(LC_ALL, "en_US.utf8");
-	size_t file_size, path_size;
-	char *file_name, *path_name;
-	char *in_file_name = (char *)smsg_in->file_name;
-	char *in_path_name = (char *)smsg_in->path_name;
-
-	file_size = wcstombs(NULL, (const wchar_t *restrict)in_file_name, 0) + 1;
-	path_size = wcstombs(NULL, (const wchar_t *restrict)in_path_name, 0) + 1;
-
-	file_name = (char *)malloc(file_size * sizeof(char));
-	path_name = (char *)malloc(path_size * sizeof(char));
-
-	if (!file_name || !path_name) {
-		free(file_name);
-		free(path_name);
-		syslog(LOG_ERR, "Can't allocate memory for file name and/or path name");
-		return HV_E_FAIL;
-	}
+	/*
+	 * file_name and path_name should have same length with appropriate
+	 * member of hv_start_fcopy.
+	 */
+	char file_name[W_MAX_PATH], path_name[W_MAX_PATH];
 
-	wcstoutf8(file_name, (__u16 *)in_file_name, file_size);
-	wcstoutf8(path_name, (__u16 *)in_path_name, path_size);
+	setlocale(LC_ALL, "en_US.utf8");
+	wcstoutf8(file_name, smsg_in->file_name, W_MAX_PATH - 1);
+	wcstoutf8(path_name, smsg_in->path_name, W_MAX_PATH - 1);
 
 	return hv_fcopy_create_file(file_name, path_name, smsg_in->copy_flags);
 }
@@ -406,7 +453,7 @@ int main(int argc, char *argv[])
 	int daemonize = 1, long_index = 0, opt, ret = -EINVAL;
 	struct vmbus_br txbr, rxbr;
 	void *ring;
-	uint32_t len = HV_RING_SIZE;
+	uint32_t ring_size, len;
 	char uio_name[NAME_MAX] = {0};
 	char uio_dev_path[PATH_MAX] = {0};
 
@@ -437,7 +484,20 @@ int main(int argc, char *argv[])
 	openlog("HV_UIO_FCOPY", 0, LOG_USER);
 	syslog(LOG_INFO, "starting; pid is:%d", getpid());
 
-	fcopy_get_first_folder(FCOPY_UIO, uio_name);
+	ring_size = get_ring_buffer_size();
+	if (!ring_size) {
+		ret = -ENODEV;
+		goto exit;
+	}
+
+	desc = malloc(ring_size * sizeof(unsigned char));
+	if (!desc) {
+		syslog(LOG_ERR, "malloc failed for desc buffer");
+		ret = -ENOMEM;
+		goto exit;
+	}
+
+	fcopy_get_first_folder(FCOPY_UIO_PATH, uio_name);
 	snprintf(uio_dev_path, sizeof(uio_dev_path), "/dev/%s", uio_name);
 	fcopy_fd = open(uio_dev_path, O_RDWR);
 
@@ -445,17 +505,17 @@ int main(int argc, char *argv[])
 		syslog(LOG_ERR, "open %s failed; error: %d %s",
 		       uio_dev_path, errno, strerror(errno));
 		ret = fcopy_fd;
-		goto exit;
+		goto free_desc;
 	}
 
-	ring = vmbus_uio_map(&fcopy_fd, HV_RING_SIZE);
+	ring = vmbus_uio_map(&fcopy_fd, ring_size);
 	if (!ring) {
 		ret = errno;
 		syslog(LOG_ERR, "mmap ringbuffer failed; error: %d %s", ret, strerror(ret));
 		goto close;
 	}
-	vmbus_br_setup(&txbr, ring, HV_RING_SIZE);
-	vmbus_br_setup(&rxbr, (char *)ring + HV_RING_SIZE, HV_RING_SIZE);
+	vmbus_br_setup(&txbr, ring, ring_size);
+	vmbus_br_setup(&rxbr, (char *)ring + ring_size, ring_size);
 
 	rxbr.vbr->imask = 0;
 
@@ -472,7 +532,7 @@ int main(int argc, char *argv[])
 			goto close;
 		}
 
-		len = HV_RING_SIZE;
+		len = ring_size;
 		ret = rte_vmbus_chan_recv_raw(&rxbr, desc, &len);
 		if (unlikely(ret <= 0)) {
 			/* This indicates a failure to communicate (or worse) */
@@ -492,6 +552,8 @@ int main(int argc, char *argv[])
 	}
 close:
 	close(fcopy_fd);
+free_desc:
+	free(desc);
 exit:
 	return ret;
 }