[PATCH 00/11] Drivers: hv: Add ARM64 support in mshv_vtl

[PATCH 00/11] Drivers: hv: Add ARM64 support in mshv_vtl

[Naman Jain]

The series intends to add support for ARM64 to mshv_vtl driver.
For this, common Hyper-V code is refactored, necessary support is added,
mshv_vtl_main.c is refactored and then finally support is added in
Kconfig.

Based on commit 1f318b96cc84 ("Linux 7.0-rc3")

Naman Jain (11):
  arch: arm64: Export arch_smp_send_reschedule for mshv_vtl module
  Drivers: hv: Move hv_vp_assist_page to common files
  Drivers: hv: Add support to setup percpu vmbus handler
  Drivers: hv: Refactor mshv_vtl for ARM64 support to be added
  drivers: hv: Export vmbus_interrupt for mshv_vtl module
  Drivers: hv: Make sint vector architecture neutral in MSHV_VTL
  arch: arm64: Add support for mshv_vtl_return_call
  Drivers: hv: mshv_vtl: Move register page config to arch-specific
    files
  Drivers: hv: mshv_vtl: Let userspace do VSM configuration
  Drivers: hv: Add support for arm64 in MSHV_VTL
  Drivers: hv: Kconfig: Add ARM64 support for MSHV_VTL

 arch/arm64/hyperv/Makefile        |   1 +
 arch/arm64/hyperv/hv_vtl.c        | 152 ++++++++++++++++++++++
 arch/arm64/hyperv/mshyperv.c      |  13 ++
 arch/arm64/include/asm/mshyperv.h |  28 ++++
 arch/arm64/kernel/smp.c           |   1 +
 arch/x86/hyperv/hv_init.c         |  88 +------------
 arch/x86/hyperv/hv_vtl.c          | 130 +++++++++++++++++++
 arch/x86/include/asm/mshyperv.h   |   8 +-
 drivers/hv/Kconfig                |   2 +-
 drivers/hv/hv_common.c            |  99 +++++++++++++++
 drivers/hv/mshv.h                 |   8 --
 drivers/hv/mshv_vtl_main.c        | 205 ++++--------------------------
 drivers/hv/vmbus_drv.c            |   8 +-
 include/asm-generic/mshyperv.h    |  49 +++++++
 include/hyperv/hvgdk_mini.h       |   2 +
 15 files changed, 505 insertions(+), 289 deletions(-)
 create mode 100644 arch/arm64/hyperv/hv_vtl.c


base-commit: 1f318b96cc84d7c2ab792fcc0bfd42a7ca890681
prerequisite-patch-id: 24022ec1fb63bc20de8114eedf03c81bb1086e0e
prerequisite-patch-id: 801f2588d5c6db4ceb9a6705a09e4649fab411b1
prerequisite-patch-id: 581c834aa268f0c54120c6efbc1393fbd9893f49
prerequisite-patch-id: b0b153807bab40860502c52e4a59297258ade0db
prerequisite-patch-id: 2bff6accea80e7976c58d80d847cd33f260a3cb9
prerequisite-patch-id: 296ffbc4f119a5b249bc9c840f84129f5c151139
prerequisite-patch-id: 3b54d121145e743ac5184518df33a1812280ec96
prerequisite-patch-id: 06fc5b37b23ee3f91a2c8c9b9c126fde290834f2
prerequisite-patch-id: 6e8afed988309b03485f5538815ea29c8fa5b0a9
prerequisite-patch-id: 4f1fb1b7e9cfa8a3b1c02fafecdbb432b74ee367
prerequisite-patch-id: 49944347e0b2d93e72911a153979c567ebb7e66b
prerequisite-patch-id: 6dec75498eeae6365d15ac12b5d0a3bd32e9f91c
-- 
2.43.0

[PATCH 01/11] arch: arm64: Export arch_smp_send_reschedule for mshv_vtl module

[Naman Jain]

mshv_vtl_main.c calls smp_send_reschedule() which expands to
arch_smp_send_reschedule(). When CONFIG_MSHV_VTL=m, the module cannot
access this symbol since it is not exported on arm64.

smp_send_reschedule() is used in mshv_vtl_cancel() to interrupt a vCPU
thread running on another CPU. When a vCPU is looping in
mshv_vtl_ioctl_return_to_lower_vtl(), it checks a per-CPU cancel flag
before each VTL0 entry. Setting cancel=1 alone is not enough if the
target CPU thread is sleeping - the IPI from smp_send_reschedule() kicks
the remote CPU out of idle/sleep so it re-checks the cancel flag and
exits the loop promptly.

Other architectures (riscv, loongarch, powerpc) already export this
symbol. Add the same EXPORT_SYMBOL_GPL for arm64. This is required
for adding arm64 support in MSHV_VTL.

Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
---
 arch/arm64/kernel/smp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 1aa324104afb..26b1a4456ceb 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -1152,6 +1152,7 @@ void arch_smp_send_reschedule(int cpu)
 {
 	smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
 }
+EXPORT_SYMBOL_GPL(arch_smp_send_reschedule);
 
 #ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
 void arch_send_wakeup_ipi(unsigned int cpu)
-- 
2.43.0

[PATCH 02/11] Drivers: hv: Move hv_vp_assist_page to common files

[Naman Jain]

Move the logic to initialize and export hv_vp_assist_page from x86
architecture code to Hyper-V common code to allow it to be used for
upcoming arm64 support in MSHV_VTL driver.
Note: This change also improves error handling - if VP assist page
allocation fails, hyperv_init() now returns early instead of
continuing with partial initialization.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
---
 arch/x86/hyperv/hv_init.c      | 88 +---------------------------------
 drivers/hv/hv_common.c         | 88 ++++++++++++++++++++++++++++++++++
 include/asm-generic/mshyperv.h |  4 ++
 include/hyperv/hvgdk_mini.h    |  2 +
 4 files changed, 95 insertions(+), 87 deletions(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 323adc93f2dc..75a98b5e451b 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -81,9 +81,6 @@ union hv_ghcb * __percpu *hv_ghcb_pg;
 /* Storage to save the hypercall page temporarily for hibernation */
 static void *hv_hypercall_pg_saved;
 
-struct hv_vp_assist_page **hv_vp_assist_page;
-EXPORT_SYMBOL_GPL(hv_vp_assist_page);
-
 static int hyperv_init_ghcb(void)
 {
 	u64 ghcb_gpa;
@@ -117,59 +114,12 @@ static int hyperv_init_ghcb(void)
 
 static int hv_cpu_init(unsigned int cpu)
 {
-	union hv_vp_assist_msr_contents msr = { 0 };
-	struct hv_vp_assist_page **hvp;
 	int ret;
 
 	ret = hv_common_cpu_init(cpu);
 	if (ret)
 		return ret;
 
-	if (!hv_vp_assist_page)
-		return 0;
-
-	hvp = &hv_vp_assist_page[cpu];
-	if (hv_root_partition()) {
-		/*
-		 * For root partition we get the hypervisor provided VP assist
-		 * page, instead of allocating a new page.
-		 */
-		rdmsrq(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
-		*hvp = memremap(msr.pfn << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT,
-				PAGE_SIZE, MEMREMAP_WB);
-	} else {
-		/*
-		 * The VP assist page is an "overlay" page (see Hyper-V TLFS's
-		 * Section 5.2.1 "GPA Overlay Pages"). Here it must be zeroed
-		 * out to make sure we always write the EOI MSR in
-		 * hv_apic_eoi_write() *after* the EOI optimization is disabled
-		 * in hv_cpu_die(), otherwise a CPU may not be stopped in the
-		 * case of CPU offlining and the VM will hang.
-		 */
-		if (!*hvp) {
-			*hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO);
-
-			/*
-			 * Hyper-V should never specify a VM that is a Confidential
-			 * VM and also running in the root partition. Root partition
-			 * is blocked to run in Confidential VM. So only decrypt assist
-			 * page in non-root partition here.
-			 */
-			if (*hvp && !ms_hyperv.paravisor_present && hv_isolation_type_snp()) {
-				WARN_ON_ONCE(set_memory_decrypted((unsigned long)(*hvp), 1));
-				memset(*hvp, 0, PAGE_SIZE);
-			}
-		}
-
-		if (*hvp)
-			msr.pfn = vmalloc_to_pfn(*hvp);
-
-	}
-	if (!WARN_ON(!(*hvp))) {
-		msr.enable = 1;
-		wrmsrq(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
-	}
-
 	/* Allow Hyper-V stimer vector to be injected from Hypervisor. */
 	if (ms_hyperv.misc_features & HV_STIMER_DIRECT_MODE_AVAILABLE)
 		apic_update_vector(cpu, HYPERV_STIMER0_VECTOR, true);
@@ -286,23 +236,6 @@ static int hv_cpu_die(unsigned int cpu)
 
 	hv_common_cpu_die(cpu);
 
-	if (hv_vp_assist_page && hv_vp_assist_page[cpu]) {
-		union hv_vp_assist_msr_contents msr = { 0 };
-		if (hv_root_partition()) {
-			/*
-			 * For root partition the VP assist page is mapped to
-			 * hypervisor provided page, and thus we unmap the
-			 * page here and nullify it, so that in future we have
-			 * correct page address mapped in hv_cpu_init.
-			 */
-			memunmap(hv_vp_assist_page[cpu]);
-			hv_vp_assist_page[cpu] = NULL;
-			rdmsrq(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
-			msr.enable = 0;
-		}
-		wrmsrq(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
-	}
-
 	if (hv_reenlightenment_cb == NULL)
 		return 0;
 
@@ -460,21 +393,6 @@ void __init hyperv_init(void)
 	if (hv_common_init())
 		return;
 
-	/*
-	 * The VP assist page is useless to a TDX guest: the only use we
-	 * would have for it is lazy EOI, which can not be used with TDX.
-	 */
-	if (hv_isolation_type_tdx())
-		hv_vp_assist_page = NULL;
-	else
-		hv_vp_assist_page = kzalloc_objs(*hv_vp_assist_page, nr_cpu_ids);
-	if (!hv_vp_assist_page) {
-		ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
-
-		if (!hv_isolation_type_tdx())
-			goto common_free;
-	}
-
 	if (ms_hyperv.paravisor_present && hv_isolation_type_snp()) {
 		/* Negotiate GHCB Version. */
 		if (!hv_ghcb_negotiate_protocol())
@@ -483,7 +401,7 @@ void __init hyperv_init(void)
 
 		hv_ghcb_pg = alloc_percpu(union hv_ghcb *);
 		if (!hv_ghcb_pg)
-			goto free_vp_assist_page;
+			goto free_ghcb_page;
 	}
 
 	cpuhp = cpuhp_setup_state(CPUHP_AP_HYPERV_ONLINE, "x86/hyperv_init:online",
@@ -613,10 +531,6 @@ void __init hyperv_init(void)
 	cpuhp_remove_state(CPUHP_AP_HYPERV_ONLINE);
 free_ghcb_page:
 	free_percpu(hv_ghcb_pg);
-free_vp_assist_page:
-	kfree(hv_vp_assist_page);
-	hv_vp_assist_page = NULL;
-common_free:
 	hv_common_free();
 }
 
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index 6b67ac616789..d1ebc0ebd08f 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -28,7 +28,9 @@
 #include <linux/slab.h>
 #include <linux/dma-map-ops.h>
 #include <linux/set_memory.h>
+#include <linux/vmalloc.h>
 #include <hyperv/hvhdk.h>
+#include <hyperv/hvgdk.h>
 #include <asm/mshyperv.h>
 
 u64 hv_current_partition_id = HV_PARTITION_ID_SELF;
@@ -78,6 +80,8 @@ static struct ctl_table_header *hv_ctl_table_hdr;
 u8 * __percpu *hv_synic_eventring_tail;
 EXPORT_SYMBOL_GPL(hv_synic_eventring_tail);
 
+struct hv_vp_assist_page **hv_vp_assist_page;
+EXPORT_SYMBOL_GPL(hv_vp_assist_page);
 /*
  * Hyper-V specific initialization and shutdown code that is
  * common across all architectures.  Called from architecture
@@ -92,6 +96,9 @@ void __init hv_common_free(void)
 	if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE)
 		hv_kmsg_dump_unregister();
 
+	kfree(hv_vp_assist_page);
+	hv_vp_assist_page = NULL;
+
 	kfree(hv_vp_index);
 	hv_vp_index = NULL;
 
@@ -394,6 +401,23 @@ int __init hv_common_init(void)
 	for (i = 0; i < nr_cpu_ids; i++)
 		hv_vp_index[i] = VP_INVAL;
 
+	/*
+	 * The VP assist page is useless to a TDX guest: the only use we
+	 * would have for it is lazy EOI, which can not be used with TDX.
+	 */
+	if (hv_isolation_type_tdx()) {
+		hv_vp_assist_page = NULL;
+	} else {
+		hv_vp_assist_page = kzalloc_objs(*hv_vp_assist_page, nr_cpu_ids);
+		if (!hv_vp_assist_page) {
+#ifdef CONFIG_X86_64
+			ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
+#endif
+			hv_common_free();
+			return -ENOMEM;
+		}
+	}
+
 	return 0;
 }
 
@@ -471,6 +495,8 @@ void __init ms_hyperv_late_init(void)
 
 int hv_common_cpu_init(unsigned int cpu)
 {
+	union hv_vp_assist_msr_contents msr = { 0 };
+	struct hv_vp_assist_page **hvp;
 	void **inputarg, **outputarg;
 	u8 **synic_eventring_tail;
 	u64 msr_vp_index;
@@ -542,6 +568,50 @@ int hv_common_cpu_init(unsigned int cpu)
 			ret = -ENOMEM;
 	}
 
+	if (!hv_vp_assist_page)
+		return ret;
+
+	hvp = &hv_vp_assist_page[cpu];
+	if (hv_root_partition()) {
+		/*
+		 * For root partition we get the hypervisor provided VP assist
+		 * page, instead of allocating a new page.
+		 */
+		msr.as_uint64 = hv_get_msr(HV_SYN_REG_VP_ASSIST_PAGE);
+		*hvp = memremap(msr.pfn << HV_VP_ASSIST_PAGE_ADDRESS_SHIFT,
+				PAGE_SIZE, MEMREMAP_WB);
+	} else {
+		/*
+		 * The VP assist page is an "overlay" page (see Hyper-V TLFS's
+		 * Section 5.2.1 "GPA Overlay Pages"). Here it must be zeroed
+		 * out to make sure we always write the EOI MSR in
+		 * hv_apic_eoi_write() *after* the EOI optimization is disabled
+		 * in hv_cpu_die(), otherwise a CPU may not be stopped in the
+		 * case of CPU offlining and the VM will hang.
+		 */
+		if (!*hvp) {
+			*hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO);
+
+			/*
+			 * Hyper-V should never specify a VM that is a Confidential
+			 * VM and also running in the root partition. Root partition
+			 * is blocked to run in Confidential VM. So only decrypt assist
+			 * page in non-root partition here.
+			 */
+			if (*hvp && !ms_hyperv.paravisor_present && hv_isolation_type_snp()) {
+				WARN_ON_ONCE(set_memory_decrypted((unsigned long)(*hvp), 1));
+				memset(*hvp, 0, PAGE_SIZE);
+			}
+		}
+
+		if (*hvp)
+			msr.pfn = vmalloc_to_pfn(*hvp);
+	}
+	if (!WARN_ON(!(*hvp))) {
+		msr.enable = 1;
+		hv_set_msr(HV_SYN_REG_VP_ASSIST_PAGE, msr.as_uint64);
+	}
+
 	return ret;
 }
 
@@ -566,6 +636,24 @@ int hv_common_cpu_die(unsigned int cpu)
 		*synic_eventring_tail = NULL;
 	}
 
+	if (hv_vp_assist_page && hv_vp_assist_page[cpu]) {
+		union hv_vp_assist_msr_contents msr = { 0 };
+
+		if (hv_root_partition()) {
+			/*
+			 * For root partition the VP assist page is mapped to
+			 * hypervisor provided page, and thus we unmap the
+			 * page here and nullify it, so that in future we have
+			 * correct page address mapped in hv_cpu_init.
+			 */
+			memunmap(hv_vp_assist_page[cpu]);
+			hv_vp_assist_page[cpu] = NULL;
+			msr.as_uint64 = hv_get_msr(HV_SYN_REG_VP_ASSIST_PAGE);
+			msr.enable = 0;
+		}
+		hv_set_msr(HV_SYN_REG_VP_ASSIST_PAGE, msr.as_uint64);
+	}
+
 	return 0;
 }
 
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index d37b68238c97..108f135d4fd9 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -25,6 +25,7 @@
 #include <linux/nmi.h>
 #include <asm/ptrace.h>
 #include <hyperv/hvhdk.h>
+#include <hyperv/hvgdk.h>
 
 #define VTPM_BASE_ADDRESS 0xfed40000
 
@@ -299,6 +300,8 @@ do { \
 #define hv_status_debug(status, fmt, ...) \
 	hv_status_printk(debug, status, fmt, ##__VA_ARGS__)
 
+extern struct hv_vp_assist_page **hv_vp_assist_page;
+
 const char *hv_result_to_string(u64 hv_status);
 int hv_result_to_errno(u64 status);
 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die);
@@ -377,6 +380,7 @@ static inline int hv_deposit_memory(u64 partition_id, u64 status)
 	return hv_deposit_memory_node(NUMA_NO_NODE, partition_id, status);
 }
 
+#define HV_VP_ASSIST_PAGE_ADDRESS_SHIFT	12
 #if IS_ENABLED(CONFIG_HYPERV_VTL_MODE)
 u8 __init get_vtl(void);
 #else
diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h
index 056ef7b6b360..be697ddb211a 100644
--- a/include/hyperv/hvgdk_mini.h
+++ b/include/hyperv/hvgdk_mini.h
@@ -149,6 +149,7 @@ struct hv_u128 {
 #define HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT	12
 #define HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_MASK	\
 		(~((1ull << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) - 1))
+#define HV_SYN_REG_VP_ASSIST_PAGE              (HV_X64_MSR_VP_ASSIST_PAGE)
 
 /* Hyper-V Enlightened VMCS version mask in nested features CPUID */
 #define HV_X64_ENLIGHTENED_VMCS_VERSION		0xff
@@ -1185,6 +1186,7 @@ enum hv_register_name {
 
 #define HV_MSR_STIMER0_CONFIG	(HV_REGISTER_STIMER0_CONFIG)
 #define HV_MSR_STIMER0_COUNT	(HV_REGISTER_STIMER0_COUNT)
+#define HV_SYN_REG_VP_ASSIST_PAGE    (HV_REGISTER_VP_ASSIST_PAGE)
 
 #endif /* CONFIG_ARM64 */
 
-- 
2.43.0

[PATCH 03/11] Drivers: hv: Add support to setup percpu vmbus handler

[Naman Jain]

Add a wrapper function - hv_setup_percpu_vmbus_handler(), similar to
hv_setup_vmbus_handler() to allow setting up custom per-cpu VMBus
interrupt handler. This is required for arm64 support, to be added
in MSHV_VTL driver, where per-cpu VMBus interrupt handler will be
set to mshv_vtl_vmbus_isr() for VTL2 (Virtual Trust Level 2).

Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
---
 arch/arm64/hyperv/mshyperv.c   | 13 +++++++++++++
 drivers/hv/hv_common.c         | 11 +++++++++++
 drivers/hv/vmbus_drv.c         |  7 +------
 include/asm-generic/mshyperv.h |  3 +++
 4 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
index 4fdc26ade1d7..d4494ceeaad0 100644
--- a/arch/arm64/hyperv/mshyperv.c
+++ b/arch/arm64/hyperv/mshyperv.c
@@ -134,3 +134,16 @@ bool hv_is_hyperv_initialized(void)
 	return hyperv_initialized;
 }
 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);
+
+static void (*vmbus_percpu_handler)(void);
+void hv_setup_percpu_vmbus_handler(void (*handler)(void))
+{
+	vmbus_percpu_handler = handler;
+}
+
+irqreturn_t vmbus_percpu_isr(int irq, void *dev_id)
+{
+	if (vmbus_percpu_handler)
+		vmbus_percpu_handler();
+	return IRQ_HANDLED;
+}
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index d1ebc0ebd08f..a5064f558bf6 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -759,6 +759,17 @@ void __weak hv_setup_vmbus_handler(void (*handler)(void))
 }
 EXPORT_SYMBOL_GPL(hv_setup_vmbus_handler);
 
+irqreturn_t __weak vmbus_percpu_isr(int irq, void *dev_id)
+{
+	return IRQ_HANDLED;
+}
+EXPORT_SYMBOL_GPL(vmbus_percpu_isr);
+
+void __weak hv_setup_percpu_vmbus_handler(void (*handler)(void))
+{
+}
+EXPORT_SYMBOL_GPL(hv_setup_percpu_vmbus_handler);
+
 void __weak hv_remove_vmbus_handler(void)
 {
 }
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index bc4fc1951ae1..f99d4f2d3862 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1413,12 +1413,6 @@ void vmbus_isr(void)
 }
 EXPORT_SYMBOL_FOR_MODULES(vmbus_isr, "mshv_vtl");
 
-static irqreturn_t vmbus_percpu_isr(int irq, void *dev_id)
-{
-	vmbus_isr();
-	return IRQ_HANDLED;
-}
-
 static void vmbus_percpu_work(struct work_struct *work)
 {
 	unsigned int cpu = smp_processor_id();
@@ -1520,6 +1514,7 @@ static int vmbus_bus_init(void)
 	if (vmbus_irq == -1) {
 		hv_setup_vmbus_handler(vmbus_isr);
 	} else {
+		hv_setup_percpu_vmbus_handler(vmbus_isr);
 		ret = request_percpu_irq(vmbus_irq, vmbus_percpu_isr,
 				"Hyper-V VMbus", &vmbus_evt);
 		if (ret) {
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index 108f135d4fd9..b147a12085e4 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -22,6 +22,7 @@
 #include <linux/bitops.h>
 #include <acpi/acpi_numa.h>
 #include <linux/cpumask.h>
+#include <linux/interrupt.h>
 #include <linux/nmi.h>
 #include <asm/ptrace.h>
 #include <hyperv/hvhdk.h>
@@ -179,6 +180,8 @@ static inline u64 hv_generate_guest_id(u64 kernel_version)
 
 int hv_get_hypervisor_version(union hv_hypervisor_version_info *info);
 
+irqreturn_t vmbus_percpu_isr(int irq, void *dev_id);
+void hv_setup_percpu_vmbus_handler(void (*handler)(void));
 void hv_setup_vmbus_handler(void (*handler)(void));
 void hv_remove_vmbus_handler(void);
 void hv_setup_stimer0_handler(void (*handler)(void));
-- 
2.43.0

[PATCH 04/11] Drivers: hv: Refactor mshv_vtl for ARM64 support to be added

[Naman Jain]

Refactor MSHV_VTL driver to move some of the x86 specific code to arch
specific files, and add corresponding functions for arm64.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
---
 arch/arm64/include/asm/mshyperv.h |  10 +++
 arch/x86/hyperv/hv_vtl.c          |  98 ++++++++++++++++++++++++++++
 arch/x86/include/asm/mshyperv.h   |   1 +
 drivers/hv/mshv_vtl_main.c        | 102 +-----------------------------
 4 files changed, 111 insertions(+), 100 deletions(-)

diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
index b721d3134ab6..804068e0941b 100644
--- a/arch/arm64/include/asm/mshyperv.h
+++ b/arch/arm64/include/asm/mshyperv.h
@@ -60,6 +60,16 @@ static inline u64 hv_get_non_nested_msr(unsigned int reg)
 				ARM_SMCCC_SMC_64,		\
 				ARM_SMCCC_OWNER_VENDOR_HYP,	\
 				HV_SMCCC_FUNC_NUMBER)
+#ifdef CONFIG_HYPERV_VTL_MODE
+/*
+ * Get/Set the register. If the function returns `1`, that must be done via
+ * a hypercall. Returning `0` means success.
+ */
+static inline int hv_vtl_get_set_reg(struct hv_register_assoc *regs, bool set, u64 shared)
+{
+	return 1;
+}
+#endif
 
 #include <asm-generic/mshyperv.h>
 
diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c
index 9b6a9bc4ab76..72a0bb4ae0c7 100644
--- a/arch/x86/hyperv/hv_vtl.c
+++ b/arch/x86/hyperv/hv_vtl.c
@@ -17,6 +17,8 @@
 #include <asm/realmode.h>
 #include <asm/reboot.h>
 #include <asm/smap.h>
+#include <uapi/asm/mtrr.h>
+#include <asm/debugreg.h>
 #include <linux/export.h>
 #include <../kernel/smpboot.h>
 #include "../../kernel/fpu/legacy.h"
@@ -281,3 +283,99 @@ void mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0)
 	kernel_fpu_end();
 }
 EXPORT_SYMBOL(mshv_vtl_return_call);
+
+/* Static table mapping register names to their corresponding actions */
+static const struct {
+	enum hv_register_name reg_name;
+	int debug_reg_num;  /* -1 if not a debug register */
+	u32 msr_addr;       /* 0 if not an MSR */
+} reg_table[] = {
+	/* Debug registers */
+	{HV_X64_REGISTER_DR0, 0, 0},
+	{HV_X64_REGISTER_DR1, 1, 0},
+	{HV_X64_REGISTER_DR2, 2, 0},
+	{HV_X64_REGISTER_DR3, 3, 0},
+	{HV_X64_REGISTER_DR6, 6, 0},
+	/* MTRR MSRs */
+	{HV_X64_REGISTER_MSR_MTRR_CAP, -1, MSR_MTRRcap},
+	{HV_X64_REGISTER_MSR_MTRR_DEF_TYPE, -1, MSR_MTRRdefType},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE0, -1, MTRRphysBase_MSR(0)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE1, -1, MTRRphysBase_MSR(1)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE2, -1, MTRRphysBase_MSR(2)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE3, -1, MTRRphysBase_MSR(3)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE4, -1, MTRRphysBase_MSR(4)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE5, -1, MTRRphysBase_MSR(5)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE6, -1, MTRRphysBase_MSR(6)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE7, -1, MTRRphysBase_MSR(7)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE8, -1, MTRRphysBase_MSR(8)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE9, -1, MTRRphysBase_MSR(9)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASEA, -1, MTRRphysBase_MSR(0xa)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASEB, -1, MTRRphysBase_MSR(0xb)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASEC, -1, MTRRphysBase_MSR(0xc)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASED, -1, MTRRphysBase_MSR(0xd)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASEE, -1, MTRRphysBase_MSR(0xe)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASEF, -1, MTRRphysBase_MSR(0xf)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK0, -1, MTRRphysMask_MSR(0)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK1, -1, MTRRphysMask_MSR(1)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK2, -1, MTRRphysMask_MSR(2)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK3, -1, MTRRphysMask_MSR(3)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK4, -1, MTRRphysMask_MSR(4)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK5, -1, MTRRphysMask_MSR(5)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK6, -1, MTRRphysMask_MSR(6)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK7, -1, MTRRphysMask_MSR(7)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK8, -1, MTRRphysMask_MSR(8)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK9, -1, MTRRphysMask_MSR(9)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKA, -1, MTRRphysMask_MSR(0xa)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKB, -1, MTRRphysMask_MSR(0xb)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKC, -1, MTRRphysMask_MSR(0xc)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKD, -1, MTRRphysMask_MSR(0xd)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKE, -1, MTRRphysMask_MSR(0xe)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKF, -1, MTRRphysMask_MSR(0xf)},
+	{HV_X64_REGISTER_MSR_MTRR_FIX64K00000, -1, MSR_MTRRfix64K_00000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX16K80000, -1, MSR_MTRRfix16K_80000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX16KA0000, -1, MSR_MTRRfix16K_A0000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX4KC0000, -1, MSR_MTRRfix4K_C0000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX4KC8000, -1, MSR_MTRRfix4K_C8000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX4KD0000, -1, MSR_MTRRfix4K_D0000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX4KD8000, -1, MSR_MTRRfix4K_D8000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX4KE0000, -1, MSR_MTRRfix4K_E0000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX4KE8000, -1, MSR_MTRRfix4K_E8000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX4KF0000, -1, MSR_MTRRfix4K_F0000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX4KF8000, -1, MSR_MTRRfix4K_F8000},
+};
+
+int hv_vtl_get_set_reg(struct hv_register_assoc *regs, bool set, u64 shared)
+{
+	u64 *reg64;
+	enum hv_register_name gpr_name;
+	int i;
+
+	gpr_name = regs->name;
+	reg64 = &regs->value.reg64;
+
+	/* Search for the register in the table */
+	for (i = 0; i < ARRAY_SIZE(reg_table); i++) {
+		if (reg_table[i].reg_name != gpr_name)
+			continue;
+		if (reg_table[i].debug_reg_num != -1) {
+			/* Handle debug registers */
+			if (gpr_name == HV_X64_REGISTER_DR6 && !shared)
+				goto hypercall;
+			if (set)
+				native_set_debugreg(reg_table[i].debug_reg_num, *reg64);
+			else
+				*reg64 = native_get_debugreg(reg_table[i].debug_reg_num);
+		} else {
+			/* Handle MSRs */
+			if (set)
+				wrmsrl(reg_table[i].msr_addr, *reg64);
+			else
+				rdmsrl(reg_table[i].msr_addr, *reg64);
+		}
+		return 0;
+	}
+
+hypercall:
+	return 1;
+}
+EXPORT_SYMBOL(hv_vtl_get_set_reg);
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index f64393e853ee..d5355a5b7517 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -304,6 +304,7 @@ void mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0);
 void mshv_vtl_return_call_init(u64 vtl_return_offset);
 void mshv_vtl_return_hypercall(void);
 void __mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0);
+int hv_vtl_get_set_reg(struct hv_register_assoc *regs, bool set, u64 shared);
 #else
 static inline void __init hv_vtl_init_platform(void) {}
 static inline int __init hv_vtl_early_init(void) { return 0; }
diff --git a/drivers/hv/mshv_vtl_main.c b/drivers/hv/mshv_vtl_main.c
index 5856975f32e1..b607b6e7e121 100644
--- a/drivers/hv/mshv_vtl_main.c
+++ b/drivers/hv/mshv_vtl_main.c
@@ -19,10 +19,8 @@
 #include <linux/poll.h>
 #include <linux/file.h>
 #include <linux/vmalloc.h>
-#include <asm/debugreg.h>
 #include <asm/mshyperv.h>
 #include <trace/events/ipi.h>
-#include <uapi/asm/mtrr.h>
 #include <uapi/linux/mshv.h>
 #include <hyperv/hvhdk.h>
 
@@ -505,102 +503,6 @@ static int mshv_vtl_ioctl_set_poll_file(struct mshv_vtl_set_poll_file __user *us
 	return 0;
 }
 
-/* Static table mapping register names to their corresponding actions */
-static const struct {
-	enum hv_register_name reg_name;
-	int debug_reg_num;  /* -1 if not a debug register */
-	u32 msr_addr;       /* 0 if not an MSR */
-} reg_table[] = {
-	/* Debug registers */
-	{HV_X64_REGISTER_DR0, 0, 0},
-	{HV_X64_REGISTER_DR1, 1, 0},
-	{HV_X64_REGISTER_DR2, 2, 0},
-	{HV_X64_REGISTER_DR3, 3, 0},
-	{HV_X64_REGISTER_DR6, 6, 0},
-	/* MTRR MSRs */
-	{HV_X64_REGISTER_MSR_MTRR_CAP, -1, MSR_MTRRcap},
-	{HV_X64_REGISTER_MSR_MTRR_DEF_TYPE, -1, MSR_MTRRdefType},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE0, -1, MTRRphysBase_MSR(0)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE1, -1, MTRRphysBase_MSR(1)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE2, -1, MTRRphysBase_MSR(2)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE3, -1, MTRRphysBase_MSR(3)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE4, -1, MTRRphysBase_MSR(4)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE5, -1, MTRRphysBase_MSR(5)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE6, -1, MTRRphysBase_MSR(6)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE7, -1, MTRRphysBase_MSR(7)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE8, -1, MTRRphysBase_MSR(8)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE9, -1, MTRRphysBase_MSR(9)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASEA, -1, MTRRphysBase_MSR(0xa)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASEB, -1, MTRRphysBase_MSR(0xb)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASEC, -1, MTRRphysBase_MSR(0xc)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASED, -1, MTRRphysBase_MSR(0xd)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASEE, -1, MTRRphysBase_MSR(0xe)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASEF, -1, MTRRphysBase_MSR(0xf)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK0, -1, MTRRphysMask_MSR(0)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK1, -1, MTRRphysMask_MSR(1)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK2, -1, MTRRphysMask_MSR(2)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK3, -1, MTRRphysMask_MSR(3)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK4, -1, MTRRphysMask_MSR(4)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK5, -1, MTRRphysMask_MSR(5)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK6, -1, MTRRphysMask_MSR(6)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK7, -1, MTRRphysMask_MSR(7)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK8, -1, MTRRphysMask_MSR(8)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK9, -1, MTRRphysMask_MSR(9)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKA, -1, MTRRphysMask_MSR(0xa)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKB, -1, MTRRphysMask_MSR(0xb)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKC, -1, MTRRphysMask_MSR(0xc)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKD, -1, MTRRphysMask_MSR(0xd)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKE, -1, MTRRphysMask_MSR(0xe)},
-	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKF, -1, MTRRphysMask_MSR(0xf)},
-	{HV_X64_REGISTER_MSR_MTRR_FIX64K00000, -1, MSR_MTRRfix64K_00000},
-	{HV_X64_REGISTER_MSR_MTRR_FIX16K80000, -1, MSR_MTRRfix16K_80000},
-	{HV_X64_REGISTER_MSR_MTRR_FIX16KA0000, -1, MSR_MTRRfix16K_A0000},
-	{HV_X64_REGISTER_MSR_MTRR_FIX4KC0000, -1, MSR_MTRRfix4K_C0000},
-	{HV_X64_REGISTER_MSR_MTRR_FIX4KC8000, -1, MSR_MTRRfix4K_C8000},
-	{HV_X64_REGISTER_MSR_MTRR_FIX4KD0000, -1, MSR_MTRRfix4K_D0000},
-	{HV_X64_REGISTER_MSR_MTRR_FIX4KD8000, -1, MSR_MTRRfix4K_D8000},
-	{HV_X64_REGISTER_MSR_MTRR_FIX4KE0000, -1, MSR_MTRRfix4K_E0000},
-	{HV_X64_REGISTER_MSR_MTRR_FIX4KE8000, -1, MSR_MTRRfix4K_E8000},
-	{HV_X64_REGISTER_MSR_MTRR_FIX4KF0000, -1, MSR_MTRRfix4K_F0000},
-	{HV_X64_REGISTER_MSR_MTRR_FIX4KF8000, -1, MSR_MTRRfix4K_F8000},
-};
-
-static int mshv_vtl_get_set_reg(struct hv_register_assoc *regs, bool set)
-{
-	u64 *reg64;
-	enum hv_register_name gpr_name;
-	int i;
-
-	gpr_name = regs->name;
-	reg64 = &regs->value.reg64;
-
-	/* Search for the register in the table */
-	for (i = 0; i < ARRAY_SIZE(reg_table); i++) {
-		if (reg_table[i].reg_name != gpr_name)
-			continue;
-		if (reg_table[i].debug_reg_num != -1) {
-			/* Handle debug registers */
-			if (gpr_name == HV_X64_REGISTER_DR6 &&
-			    !mshv_vsm_capabilities.dr6_shared)
-				goto hypercall;
-			if (set)
-				native_set_debugreg(reg_table[i].debug_reg_num, *reg64);
-			else
-				*reg64 = native_get_debugreg(reg_table[i].debug_reg_num);
-		} else {
-			/* Handle MSRs */
-			if (set)
-				wrmsrl(reg_table[i].msr_addr, *reg64);
-			else
-				rdmsrl(reg_table[i].msr_addr, *reg64);
-		}
-		return 0;
-	}
-
-hypercall:
-	return 1;
-}
-
 static void mshv_vtl_return(struct mshv_vtl_cpu_context *vtl0)
 {
 	struct hv_vp_assist_page *hvp;
@@ -720,7 +622,7 @@ mshv_vtl_ioctl_get_regs(void __user *user_args)
 			   sizeof(reg)))
 		return -EFAULT;
 
-	ret = mshv_vtl_get_set_reg(&reg, false);
+	ret = hv_vtl_get_set_reg(&reg, false, mshv_vsm_capabilities.dr6_shared);
 	if (!ret)
 		goto copy_args; /* No need of hypercall */
 	ret = vtl_get_vp_register(&reg);
@@ -751,7 +653,7 @@ mshv_vtl_ioctl_set_regs(void __user *user_args)
 	if (copy_from_user(&reg, (void __user *)args.regs_ptr, sizeof(reg)))
 		return -EFAULT;
 
-	ret = mshv_vtl_get_set_reg(&reg, true);
+	ret = hv_vtl_get_set_reg(&reg, true, mshv_vsm_capabilities.dr6_shared);
 	if (!ret)
 		return ret; /* No need of hypercall */
 	ret = vtl_set_vp_register(&reg);
-- 
2.43.0

[PATCH 05/11] drivers: hv: Export vmbus_interrupt for mshv_vtl module

[Naman Jain]

vmbus_interrupt is used in mshv_vtl_main.c to set the SINT vector.
When CONFIG_MSHV_VTL=m and CONFIG_HYPERV_VMBUS=y (built-in), the module
cannot access vmbus_interrupt at load time since it is not exported.

Export it using EXPORT_SYMBOL_FOR_MODULES consistent with the existing
pattern used for vmbus_isr.

Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
---
 drivers/hv/vmbus_drv.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index f99d4f2d3862..de191799a8f6 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -57,6 +57,7 @@ static DEFINE_PER_CPU(long, vmbus_evt);
 /* Values parsed from ACPI DSDT */
 int vmbus_irq;
 int vmbus_interrupt;
+EXPORT_SYMBOL_FOR_MODULES(vmbus_interrupt, "mshv_vtl");
 
 /*
  * If the Confidential VMBus is used, the data on the "wire" is not
-- 
2.43.0

[PATCH 06/11] Drivers: hv: Make sint vector architecture neutral in MSHV_VTL

[Naman Jain]

Generalize Synthetic interrupt source vector (sint) to use
vmbus_interrupt variable instead, which automatically takes care of
architectures where HYPERVISOR_CALLBACK_VECTOR is not present (arm64).

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
---
 drivers/hv/mshv_vtl_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hv/mshv_vtl_main.c b/drivers/hv/mshv_vtl_main.c
index b607b6e7e121..91517b45d526 100644
--- a/drivers/hv/mshv_vtl_main.c
+++ b/drivers/hv/mshv_vtl_main.c
@@ -234,7 +234,7 @@ static void mshv_vtl_synic_enable_regs(unsigned int cpu)
 	union hv_synic_sint sint;
 
 	sint.as_uint64 = 0;
-	sint.vector = HYPERVISOR_CALLBACK_VECTOR;
+	sint.vector = vmbus_interrupt;
 	sint.masked = false;
 	sint.auto_eoi = hv_recommend_using_aeoi();
 
@@ -753,7 +753,7 @@ static void mshv_vtl_synic_mask_vmbus_sint(void *info)
 	const u8 *mask = info;
 
 	sint.as_uint64 = 0;
-	sint.vector = HYPERVISOR_CALLBACK_VECTOR;
+	sint.vector = vmbus_interrupt;
 	sint.masked = (*mask != 0);
 	sint.auto_eoi = hv_recommend_using_aeoi();
 
-- 
2.43.0

[PATCH 07/11] arch: arm64: Add support for mshv_vtl_return_call

[Naman Jain]

Add support for arm64 specific variant of mshv_vtl_return_call function
to be able to add support for arm64 in MSHV_VTL driver. This would
help enable the transition between Virtual Trust Levels (VTL) in
MSHV_VTL when the kernel acts as a paravisor.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
---
 arch/arm64/hyperv/Makefile        |   1 +
 arch/arm64/hyperv/hv_vtl.c        | 144 ++++++++++++++++++++++++++++++
 arch/arm64/include/asm/mshyperv.h |  13 +++
 3 files changed, 158 insertions(+)
 create mode 100644 arch/arm64/hyperv/hv_vtl.c

diff --git a/arch/arm64/hyperv/Makefile b/arch/arm64/hyperv/Makefile
index 87c31c001da9..9701a837a6e1 100644
--- a/arch/arm64/hyperv/Makefile
+++ b/arch/arm64/hyperv/Makefile
@@ -1,2 +1,3 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-y		:= hv_core.o mshyperv.o
+obj-$(CONFIG_HYPERV_VTL_MODE)	+= hv_vtl.o
diff --git a/arch/arm64/hyperv/hv_vtl.c b/arch/arm64/hyperv/hv_vtl.c
new file mode 100644
index 000000000000..66318672c242
--- /dev/null
+++ b/arch/arm64/hyperv/hv_vtl.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2026, Microsoft, Inc.
+ *
+ * Authors:
+ *     Roman Kisel <romank@linux.microsoft.com>
+ *     Naman Jain <namjain@linux.microsoft.com>
+ */
+
+#include <asm/boot.h>
+#include <asm/mshyperv.h>
+#include <asm/cpu_ops.h>
+
+void mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0)
+{
+	u64 base_ptr = (u64)vtl0->x;
+
+	/*
+	 * VTL switch for ARM64 platform - managing VTL0's CPU context.
+	 * We explicitly use the stack to save the base pointer, and use x16
+	 * as our working register for accessing the context structure.
+	 *
+	 * Register Handling:
+	 * - X0-X17: Saved/restored (general-purpose, shared for VTL communication)
+	 * - X18: NOT touched - hypervisor-managed per-VTL (platform register)
+	 * - X19-X30: Saved/restored (part of VTL0's execution context)
+	 * - Q0-Q31: Saved/restored (128-bit NEON/floating-point registers, shared)
+	 * - SP: Not in structure, hypervisor-managed per-VTL
+	 *
+	 * Note: X29 (FP) and X30 (LR) are in the structure and must be saved/restored
+	 * as part of VTL0's complete execution state.
+	 */
+	asm __volatile__ (
+		/* Save base pointer to stack explicitly, then load into x16 */
+		"str %0, [sp, #-16]!\n\t"     /* Push base pointer onto stack */
+		"mov x16, %0\n\t"             /* Load base pointer into x16 */
+		/* Volatile registers (Windows ARM64 ABI: x0-x15) */
+		"ldp x0, x1, [x16]\n\t"
+		"ldp x2, x3, [x16, #(2*8)]\n\t"
+		"ldp x4, x5, [x16, #(4*8)]\n\t"
+		"ldp x6, x7, [x16, #(6*8)]\n\t"
+		"ldp x8, x9, [x16, #(8*8)]\n\t"
+		"ldp x10, x11, [x16, #(10*8)]\n\t"
+		"ldp x12, x13, [x16, #(12*8)]\n\t"
+		"ldp x14, x15, [x16, #(14*8)]\n\t"
+		/* x16 will be loaded last, after saving base pointer */
+		"ldr x17, [x16, #(17*8)]\n\t"
+		/* x18 is hypervisor-managed per-VTL - DO NOT LOAD */
+
+		/* General-purpose registers: x19-x30 */
+		"ldp x19, x20, [x16, #(19*8)]\n\t"
+		"ldp x21, x22, [x16, #(21*8)]\n\t"
+		"ldp x23, x24, [x16, #(23*8)]\n\t"
+		"ldp x25, x26, [x16, #(25*8)]\n\t"
+		"ldp x27, x28, [x16, #(27*8)]\n\t"
+
+		/* Frame pointer and link register */
+		"ldp x29, x30, [x16, #(29*8)]\n\t"
+
+		/* Shared NEON/FP registers: Q0-Q31 (128-bit) */
+		"ldp q0, q1, [x16, #(32*8)]\n\t"
+		"ldp q2, q3, [x16, #(32*8 + 2*16)]\n\t"
+		"ldp q4, q5, [x16, #(32*8 + 4*16)]\n\t"
+		"ldp q6, q7, [x16, #(32*8 + 6*16)]\n\t"
+		"ldp q8, q9, [x16, #(32*8 + 8*16)]\n\t"
+		"ldp q10, q11, [x16, #(32*8 + 10*16)]\n\t"
+		"ldp q12, q13, [x16, #(32*8 + 12*16)]\n\t"
+		"ldp q14, q15, [x16, #(32*8 + 14*16)]\n\t"
+		"ldp q16, q17, [x16, #(32*8 + 16*16)]\n\t"
+		"ldp q18, q19, [x16, #(32*8 + 18*16)]\n\t"
+		"ldp q20, q21, [x16, #(32*8 + 20*16)]\n\t"
+		"ldp q22, q23, [x16, #(32*8 + 22*16)]\n\t"
+		"ldp q24, q25, [x16, #(32*8 + 24*16)]\n\t"
+		"ldp q26, q27, [x16, #(32*8 + 26*16)]\n\t"
+		"ldp q28, q29, [x16, #(32*8 + 28*16)]\n\t"
+		"ldp q30, q31, [x16, #(32*8 + 30*16)]\n\t"
+
+		/* Now load x16 itself */
+		"ldr x16, [x16, #(16*8)]\n\t"
+
+		/* Return to the lower VTL */
+		"hvc #3\n\t"
+
+		/* Save context after return - reload base pointer from stack */
+		"stp x16, x17, [sp, #-16]!\n\t" /* Save x16, x17 temporarily */
+		"ldr x16, [sp, #16]\n\t"        /* Reload base pointer (skip saved x16,x17) */
+
+		/* Volatile registers */
+		"stp x0, x1, [x16]\n\t"
+		"stp x2, x3, [x16, #(2*8)]\n\t"
+		"stp x4, x5, [x16, #(4*8)]\n\t"
+		"stp x6, x7, [x16, #(6*8)]\n\t"
+		"stp x8, x9, [x16, #(8*8)]\n\t"
+		"stp x10, x11, [x16, #(10*8)]\n\t"
+		"stp x12, x13, [x16, #(12*8)]\n\t"
+		"stp x14, x15, [x16, #(14*8)]\n\t"
+		"ldp x0, x1, [sp], #16\n\t"      /* Recover saved x16, x17 */
+		"stp x0, x1, [x16, #(16*8)]\n\t"
+		/* x18 is hypervisor-managed - DO NOT SAVE */
+
+		/* General-purpose registers: x19-x30 */
+		"stp x19, x20, [x16, #(19*8)]\n\t"
+		"stp x21, x22, [x16, #(21*8)]\n\t"
+		"stp x23, x24, [x16, #(23*8)]\n\t"
+		"stp x25, x26, [x16, #(25*8)]\n\t"
+		"stp x27, x28, [x16, #(27*8)]\n\t"
+		"stp x29, x30, [x16, #(29*8)]\n\t"  /* Frame pointer and link register */
+
+		/* Shared NEON/FP registers: Q0-Q31 (128-bit) */
+		"stp q0, q1, [x16, #(32*8)]\n\t"
+		"stp q2, q3, [x16, #(32*8 + 2*16)]\n\t"
+		"stp q4, q5, [x16, #(32*8 + 4*16)]\n\t"
+		"stp q6, q7, [x16, #(32*8 + 6*16)]\n\t"
+		"stp q8, q9, [x16, #(32*8 + 8*16)]\n\t"
+		"stp q10, q11, [x16, #(32*8 + 10*16)]\n\t"
+		"stp q12, q13, [x16, #(32*8 + 12*16)]\n\t"
+		"stp q14, q15, [x16, #(32*8 + 14*16)]\n\t"
+		"stp q16, q17, [x16, #(32*8 + 16*16)]\n\t"
+		"stp q18, q19, [x16, #(32*8 + 18*16)]\n\t"
+		"stp q20, q21, [x16, #(32*8 + 20*16)]\n\t"
+		"stp q22, q23, [x16, #(32*8 + 22*16)]\n\t"
+		"stp q24, q25, [x16, #(32*8 + 24*16)]\n\t"
+		"stp q26, q27, [x16, #(32*8 + 26*16)]\n\t"
+		"stp q28, q29, [x16, #(32*8 + 28*16)]\n\t"
+		"stp q30, q31, [x16, #(32*8 + 30*16)]\n\t"
+
+		/* Clean up stack - pop base pointer */
+		"add sp, sp, #16\n\t"
+
+		: /* No outputs */
+		: /* Input */ "r"(base_ptr)
+		: /* Clobber list - x16 used as base, x18 is hypervisor-managed (not touched) */
+		"memory", "cc",
+		"x0", "x1", "x2", "x3", "x4", "x5",
+		"x6", "x7", "x8", "x9", "x10", "x11", "x12", "x13",
+		"x14", "x15", "x16", "x17", "x19", "x20", "x21",
+		"x22", "x23", "x24", "x25", "x26", "x27", "x28",
+		"x29", "x30",
+		"v0", "v1", "v2", "v3", "v4", "v5", "v6", "v7",
+		"v8", "v9", "v10", "v11", "v12", "v13", "v14", "v15",
+		"v16", "v17", "v18", "v19", "v20", "v21", "v22", "v23",
+		"v24", "v25", "v26", "v27", "v28", "v29", "v30", "v31");
+}
+EXPORT_SYMBOL(mshv_vtl_return_call);
diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
index 804068e0941b..de7f3a41a8ea 100644
--- a/arch/arm64/include/asm/mshyperv.h
+++ b/arch/arm64/include/asm/mshyperv.h
@@ -60,6 +60,17 @@ static inline u64 hv_get_non_nested_msr(unsigned int reg)
 				ARM_SMCCC_SMC_64,		\
 				ARM_SMCCC_OWNER_VENDOR_HYP,	\
 				HV_SMCCC_FUNC_NUMBER)
+
+struct mshv_vtl_cpu_context {
+/*
+ * NOTE: x18 is managed by the hypervisor. It won't be reloaded from this array.
+ * It is included here for convenience in the common case.
+ */
+	__u64 x[31];
+	__u64 rsvd;
+	__uint128_t q[32];
+};
+
 #ifdef CONFIG_HYPERV_VTL_MODE
 /*
  * Get/Set the register. If the function returns `1`, that must be done via
@@ -69,6 +80,8 @@ static inline int hv_vtl_get_set_reg(struct hv_register_assoc *regs, bool set, u
 {
 	return 1;
 }
+
+void mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0);
 #endif
 
 #include <asm-generic/mshyperv.h>
-- 
2.43.0

[PATCH 08/11] Drivers: hv: mshv_vtl: Move register page config to arch-specific files

[Naman Jain]

Move mshv_vtl_configure_reg_page() implementation from
drivers/hv/mshv_vtl_main.c to arch-specific files:
- arch/x86/hyperv/hv_vtl.c: full implementation with register page setup
- arch/arm64/hyperv/hv_vtl.c: stub implementation (unsupported)

Move common type definitions to include/asm-generic/mshyperv.h:
- struct mshv_vtl_per_cpu
- union hv_synic_overlay_page_msr

Move hv_call_get_vp_registers() and hv_call_set_vp_registers()
declarations to include/asm-generic/mshyperv.h since these functions
are used by multiple modules.

While at it, remove the unnecessary stub implementations in #else
case for mshv_vtl_return* functions in arch/x86/include/asm/mshyperv.h.

This is essential for adding support for ARM64 in MSHV_VTL.

Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
---
 arch/arm64/hyperv/hv_vtl.c        |  8 +++++
 arch/arm64/include/asm/mshyperv.h |  3 ++
 arch/x86/hyperv/hv_vtl.c          | 32 ++++++++++++++++++++
 arch/x86/include/asm/mshyperv.h   |  7 ++---
 drivers/hv/mshv.h                 |  8 -----
 drivers/hv/mshv_vtl_main.c        | 49 +++----------------------------
 include/asm-generic/mshyperv.h    | 42 ++++++++++++++++++++++++++
 7 files changed, 92 insertions(+), 57 deletions(-)

diff --git a/arch/arm64/hyperv/hv_vtl.c b/arch/arm64/hyperv/hv_vtl.c
index 66318672c242..d699138427c1 100644
--- a/arch/arm64/hyperv/hv_vtl.c
+++ b/arch/arm64/hyperv/hv_vtl.c
@@ -10,6 +10,7 @@
 #include <asm/boot.h>
 #include <asm/mshyperv.h>
 #include <asm/cpu_ops.h>
+#include <linux/export.h>
 
 void mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0)
 {
@@ -142,3 +143,10 @@ void mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0)
 		"v24", "v25", "v26", "v27", "v28", "v29", "v30", "v31");
 }
 EXPORT_SYMBOL(mshv_vtl_return_call);
+
+bool hv_vtl_configure_reg_page(struct mshv_vtl_per_cpu *per_cpu)
+{
+	pr_debug("Register page not supported on ARM64\n");
+	return false;
+}
+EXPORT_SYMBOL_GPL(hv_vtl_configure_reg_page);
diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
index de7f3a41a8ea..36803f0386cc 100644
--- a/arch/arm64/include/asm/mshyperv.h
+++ b/arch/arm64/include/asm/mshyperv.h
@@ -61,6 +61,8 @@ static inline u64 hv_get_non_nested_msr(unsigned int reg)
 				ARM_SMCCC_OWNER_VENDOR_HYP,	\
 				HV_SMCCC_FUNC_NUMBER)
 
+struct mshv_vtl_per_cpu;
+
 struct mshv_vtl_cpu_context {
 /*
  * NOTE: x18 is managed by the hypervisor. It won't be reloaded from this array.
@@ -82,6 +84,7 @@ static inline int hv_vtl_get_set_reg(struct hv_register_assoc *regs, bool set, u
 }
 
 void mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0);
+bool hv_vtl_configure_reg_page(struct mshv_vtl_per_cpu *per_cpu);
 #endif
 
 #include <asm-generic/mshyperv.h>
diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c
index 72a0bb4ae0c7..ede290985d41 100644
--- a/arch/x86/hyperv/hv_vtl.c
+++ b/arch/x86/hyperv/hv_vtl.c
@@ -20,6 +20,7 @@
 #include <uapi/asm/mtrr.h>
 #include <asm/debugreg.h>
 #include <linux/export.h>
+#include <linux/hyperv.h>
 #include <../kernel/smpboot.h>
 #include "../../kernel/fpu/legacy.h"
 
@@ -259,6 +260,37 @@ int __init hv_vtl_early_init(void)
 	return 0;
 }
 
+static const union hv_input_vtl input_vtl_zero;
+
+bool hv_vtl_configure_reg_page(struct mshv_vtl_per_cpu *per_cpu)
+{
+	struct hv_register_assoc reg_assoc = {};
+	union hv_synic_overlay_page_msr overlay = {};
+	struct page *reg_page;
+
+	reg_page = alloc_page(GFP_KERNEL | __GFP_ZERO | __GFP_RETRY_MAYFAIL);
+	if (!reg_page) {
+		WARN(1, "failed to allocate register page\n");
+		return false;
+	}
+
+	overlay.enabled = 1;
+	overlay.pfn = page_to_hvpfn(reg_page);
+	reg_assoc.name = HV_X64_REGISTER_REG_PAGE;
+	reg_assoc.value.reg64 = overlay.as_uint64;
+
+	if (hv_call_set_vp_registers(HV_VP_INDEX_SELF, HV_PARTITION_ID_SELF,
+				     1, input_vtl_zero, &reg_assoc)) {
+		WARN(1, "failed to setup register page\n");
+		__free_page(reg_page);
+		return false;
+	}
+
+	per_cpu->reg_page = reg_page;
+	return true;
+}
+EXPORT_SYMBOL_GPL(hv_vtl_configure_reg_page);
+
 DEFINE_STATIC_CALL_NULL(__mshv_vtl_return_hypercall, void (*)(void));
 
 void mshv_vtl_return_call_init(u64 vtl_return_offset)
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index d5355a5b7517..d592fea49cdb 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -271,6 +271,8 @@ static inline u64 hv_get_non_nested_msr(unsigned int reg) { return 0; }
 static inline int hv_apicid_to_vp_index(u32 apic_id) { return -EINVAL; }
 #endif /* CONFIG_HYPERV */
 
+struct mshv_vtl_per_cpu;
+
 struct mshv_vtl_cpu_context {
 	union {
 		struct {
@@ -305,13 +307,10 @@ void mshv_vtl_return_call_init(u64 vtl_return_offset);
 void mshv_vtl_return_hypercall(void);
 void __mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0);
 int hv_vtl_get_set_reg(struct hv_register_assoc *regs, bool set, u64 shared);
+bool hv_vtl_configure_reg_page(struct mshv_vtl_per_cpu *per_cpu);
 #else
 static inline void __init hv_vtl_init_platform(void) {}
 static inline int __init hv_vtl_early_init(void) { return 0; }
-static inline void mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0) {}
-static inline void mshv_vtl_return_call_init(u64 vtl_return_offset) {}
-static inline void mshv_vtl_return_hypercall(void) {}
-static inline void __mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0) {}
 #endif
 
 #include <asm-generic/mshyperv.h>
diff --git a/drivers/hv/mshv.h b/drivers/hv/mshv.h
index d4813df92b9c..0fcb7f9ba6a9 100644
--- a/drivers/hv/mshv.h
+++ b/drivers/hv/mshv.h
@@ -14,14 +14,6 @@
 	memchr_inv(&((STRUCT).MEMBER), \
 		   0, sizeof_field(typeof(STRUCT), MEMBER))
 
-int hv_call_get_vp_registers(u32 vp_index, u64 partition_id, u16 count,
-			     union hv_input_vtl input_vtl,
-			     struct hv_register_assoc *registers);
-
-int hv_call_set_vp_registers(u32 vp_index, u64 partition_id, u16 count,
-			     union hv_input_vtl input_vtl,
-			     struct hv_register_assoc *registers);
-
 int hv_call_get_partition_property(u64 partition_id, u64 property_code,
 				   u64 *property_value);
 
diff --git a/drivers/hv/mshv_vtl_main.c b/drivers/hv/mshv_vtl_main.c
index 91517b45d526..c79d24317b8e 100644
--- a/drivers/hv/mshv_vtl_main.c
+++ b/drivers/hv/mshv_vtl_main.c
@@ -78,21 +78,6 @@ struct mshv_vtl {
 	u64 id;
 };
 
-struct mshv_vtl_per_cpu {
-	struct mshv_vtl_run *run;
-	struct page *reg_page;
-};
-
-/* SYNIC_OVERLAY_PAGE_MSR - internal, identical to hv_synic_simp */
-union hv_synic_overlay_page_msr {
-	u64 as_uint64;
-	struct {
-		u64 enabled: 1;
-		u64 reserved: 11;
-		u64 pfn: 52;
-	} __packed;
-};
-
 static struct mutex mshv_vtl_poll_file_lock;
 static union hv_register_vsm_page_offsets mshv_vsm_page_offsets;
 static union hv_register_vsm_capabilities mshv_vsm_capabilities;
@@ -201,34 +186,6 @@ static struct page *mshv_vtl_cpu_reg_page(int cpu)
 	return *per_cpu_ptr(&mshv_vtl_per_cpu.reg_page, cpu);
 }
 
-static void mshv_vtl_configure_reg_page(struct mshv_vtl_per_cpu *per_cpu)
-{
-	struct hv_register_assoc reg_assoc = {};
-	union hv_synic_overlay_page_msr overlay = {};
-	struct page *reg_page;
-
-	reg_page = alloc_page(GFP_KERNEL | __GFP_ZERO | __GFP_RETRY_MAYFAIL);
-	if (!reg_page) {
-		WARN(1, "failed to allocate register page\n");
-		return;
-	}
-
-	overlay.enabled = 1;
-	overlay.pfn = page_to_hvpfn(reg_page);
-	reg_assoc.name = HV_X64_REGISTER_REG_PAGE;
-	reg_assoc.value.reg64 = overlay.as_uint64;
-
-	if (hv_call_set_vp_registers(HV_VP_INDEX_SELF, HV_PARTITION_ID_SELF,
-				     1, input_vtl_zero, &reg_assoc)) {
-		WARN(1, "failed to setup register page\n");
-		__free_page(reg_page);
-		return;
-	}
-
-	per_cpu->reg_page = reg_page;
-	mshv_has_reg_page = true;
-}
-
 static void mshv_vtl_synic_enable_regs(unsigned int cpu)
 {
 	union hv_synic_sint sint;
@@ -329,8 +286,10 @@ static int mshv_vtl_alloc_context(unsigned int cpu)
 	if (!per_cpu->run)
 		return -ENOMEM;
 
-	if (mshv_vsm_capabilities.intercept_page_available)
-		mshv_vtl_configure_reg_page(per_cpu);
+	if (mshv_vsm_capabilities.intercept_page_available) {
+		if (hv_vtl_configure_reg_page(per_cpu))
+			mshv_has_reg_page = true;
+	}
 
 	mshv_vtl_synic_enable_regs(cpu);
 
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index b147a12085e4..b53fcc071596 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -383,8 +383,50 @@ static inline int hv_deposit_memory(u64 partition_id, u64 status)
 	return hv_deposit_memory_node(NUMA_NO_NODE, partition_id, status);
 }
 
+#if IS_ENABLED(CONFIG_MSHV_ROOT) || IS_ENABLED(CONFIG_MSHV_VTL)
+int hv_call_get_vp_registers(u32 vp_index, u64 partition_id, u16 count,
+			     union hv_input_vtl input_vtl,
+			     struct hv_register_assoc *registers);
+
+int hv_call_set_vp_registers(u32 vp_index, u64 partition_id, u16 count,
+			     union hv_input_vtl input_vtl,
+			     struct hv_register_assoc *registers);
+#else
+static inline int hv_call_get_vp_registers(u32 vp_index, u64 partition_id,
+					   u16 count,
+					   union hv_input_vtl input_vtl,
+					   struct hv_register_assoc *registers)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int hv_call_set_vp_registers(u32 vp_index, u64 partition_id,
+					   u16 count,
+					   union hv_input_vtl input_vtl,
+					   struct hv_register_assoc *registers)
+{
+	return -EOPNOTSUPP;
+}
+#endif /* CONFIG_MSHV_ROOT || CONFIG_MSHV_VTL */
+
 #define HV_VP_ASSIST_PAGE_ADDRESS_SHIFT	12
+
 #if IS_ENABLED(CONFIG_HYPERV_VTL_MODE)
+struct mshv_vtl_per_cpu {
+	struct mshv_vtl_run *run;
+	struct page *reg_page;
+};
+
+/* SYNIC_OVERLAY_PAGE_MSR - internal, identical to hv_synic_simp */
+union hv_synic_overlay_page_msr {
+	u64 as_uint64;
+	struct {
+		u64 enabled: 1;
+		u64 reserved: 11;
+		u64 pfn: 52;
+	} __packed;
+};
+
 u8 __init get_vtl(void);
 #else
 static inline u8 get_vtl(void) { return 0; }
-- 
2.43.0

[PATCH 09/11] Drivers: hv: mshv_vtl: Let userspace do VSM configuration

[Naman Jain]

The kernel currently sets the VSM configuration register, thereby
imposing certain VSM configuration on the userspace (OpenVMM).

The userspace (OpenVMM) has the capability to configure this register,
and it is already doing it using the generic hypercall interface.
The configuration can vary based on the use case or architectures, so
let userspace take care of configuring it and remove this logic in the
kernel driver.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
---
 drivers/hv/mshv_vtl_main.c | 29 -----------------------------
 1 file changed, 29 deletions(-)

diff --git a/drivers/hv/mshv_vtl_main.c b/drivers/hv/mshv_vtl_main.c
index c79d24317b8e..4c9ae65ad3e8 100644
--- a/drivers/hv/mshv_vtl_main.c
+++ b/drivers/hv/mshv_vtl_main.c
@@ -222,30 +222,6 @@ static int mshv_vtl_get_vsm_regs(void)
 	return ret;
 }
 
-static int mshv_vtl_configure_vsm_partition(struct device *dev)
-{
-	union hv_register_vsm_partition_config config;
-	struct hv_register_assoc reg_assoc;
-
-	config.as_uint64 = 0;
-	config.default_vtl_protection_mask = HV_MAP_GPA_PERMISSIONS_MASK;
-	config.enable_vtl_protection = 1;
-	config.zero_memory_on_reset = 1;
-	config.intercept_vp_startup = 1;
-	config.intercept_cpuid_unimplemented = 1;
-
-	if (mshv_vsm_capabilities.intercept_page_available) {
-		dev_dbg(dev, "using intercept page\n");
-		config.intercept_page = 1;
-	}
-
-	reg_assoc.name = HV_REGISTER_VSM_PARTITION_CONFIG;
-	reg_assoc.value.reg64 = config.as_uint64;
-
-	return hv_call_set_vp_registers(HV_VP_INDEX_SELF, HV_PARTITION_ID_SELF,
-				       1, input_vtl_zero, &reg_assoc);
-}
-
 static void mshv_vtl_vmbus_isr(void)
 {
 	struct hv_per_cpu_context *per_cpu;
@@ -1168,11 +1144,6 @@ static int __init mshv_vtl_init(void)
 		ret = -ENODEV;
 		goto free_dev;
 	}
-	if (mshv_vtl_configure_vsm_partition(dev)) {
-		dev_emerg(dev, "VSM configuration failed !!\n");
-		ret = -ENODEV;
-		goto free_dev;
-	}
 
 	mshv_vtl_return_call_init(mshv_vsm_page_offsets.vtl_return_offset);
 	ret = hv_vtl_setup_synic();
-- 
2.43.0

[PATCH 10/11] Drivers: hv: Add support for arm64 in MSHV_VTL

[Naman Jain]

Add necessary support to make MSHV_VTL work for arm64 architecture.
* Add stub implementation for mshv_vtl_return_call_init(): not required
  for arm64
* Remove fpu/legacy.h header inclusion, as this is not required
* handle HV_REGISTER_VSM_CODE_PAGE_OFFSETS register: not supported
  in arm64
* Configure custom percpu_vmbus_handler by using
  hv_setup_percpu_vmbus_handler()
* Handle hugepage functions by config checks

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
---
 arch/arm64/include/asm/mshyperv.h |  2 ++
 drivers/hv/mshv_vtl_main.c        | 21 ++++++++++++++-------
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
index 36803f0386cc..027a7f062d70 100644
--- a/arch/arm64/include/asm/mshyperv.h
+++ b/arch/arm64/include/asm/mshyperv.h
@@ -83,6 +83,8 @@ static inline int hv_vtl_get_set_reg(struct hv_register_assoc *regs, bool set, u
 	return 1;
 }
 
+static inline void mshv_vtl_return_call_init(u64 vtl_return_offset) {}
+
 void mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0);
 bool hv_vtl_configure_reg_page(struct mshv_vtl_per_cpu *per_cpu);
 #endif
diff --git a/drivers/hv/mshv_vtl_main.c b/drivers/hv/mshv_vtl_main.c
index 4c9ae65ad3e8..5702fe258500 100644
--- a/drivers/hv/mshv_vtl_main.c
+++ b/drivers/hv/mshv_vtl_main.c
@@ -23,8 +23,6 @@
 #include <trace/events/ipi.h>
 #include <uapi/linux/mshv.h>
 #include <hyperv/hvhdk.h>
-
-#include "../../kernel/fpu/legacy.h"
 #include "mshv.h"
 #include "mshv_vtl.h"
 #include "hyperv_vmbus.h"
@@ -206,18 +204,21 @@ static void mshv_vtl_synic_enable_regs(unsigned int cpu)
 static int mshv_vtl_get_vsm_regs(void)
 {
 	struct hv_register_assoc registers[2];
-	int ret, count = 2;
+	int ret, count = 0;
 
-	registers[0].name = HV_REGISTER_VSM_CODE_PAGE_OFFSETS;
-	registers[1].name = HV_REGISTER_VSM_CAPABILITIES;
+	registers[count++].name = HV_REGISTER_VSM_CAPABILITIES;
+	/* Code page offset register is not supported on ARM */
+	if (IS_ENABLED(CONFIG_X86_64))
+		registers[count++].name = HV_REGISTER_VSM_CODE_PAGE_OFFSETS;
 
 	ret = hv_call_get_vp_registers(HV_VP_INDEX_SELF, HV_PARTITION_ID_SELF,
 				       count, input_vtl_zero, registers);
 	if (ret)
 		return ret;
 
-	mshv_vsm_page_offsets.as_uint64 = registers[0].value.reg64;
-	mshv_vsm_capabilities.as_uint64 = registers[1].value.reg64;
+	mshv_vsm_capabilities.as_uint64 = registers[0].value.reg64;
+	if (IS_ENABLED(CONFIG_X86_64))
+		mshv_vsm_page_offsets.as_uint64 = registers[1].value.reg64;
 
 	return ret;
 }
@@ -280,10 +281,13 @@ static int hv_vtl_setup_synic(void)
 
 	/* Use our isr to first filter out packets destined for userspace */
 	hv_setup_vmbus_handler(mshv_vtl_vmbus_isr);
+	/* hv_setup_vmbus_handler() is stubbed for ARM64, add per-cpu VMBus handlers instead */
+	hv_setup_percpu_vmbus_handler(mshv_vtl_vmbus_isr);
 
 	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "hyperv/vtl:online",
 				mshv_vtl_alloc_context, NULL);
 	if (ret < 0) {
+		hv_setup_percpu_vmbus_handler(vmbus_isr);
 		hv_setup_vmbus_handler(vmbus_isr);
 		return ret;
 	}
@@ -296,6 +300,7 @@ static int hv_vtl_setup_synic(void)
 static void hv_vtl_remove_synic(void)
 {
 	cpuhp_remove_state(mshv_vtl_cpuhp_online);
+	hv_setup_percpu_vmbus_handler(vmbus_isr);
 	hv_setup_vmbus_handler(vmbus_isr);
 }
 
@@ -1080,10 +1085,12 @@ static vm_fault_t mshv_vtl_low_huge_fault(struct vm_fault *vmf, unsigned int ord
 			ret = vmf_insert_pfn_pmd(vmf, pfn, vmf->flags & FAULT_FLAG_WRITE);
 		return ret;
 
+#if defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
 	case PUD_ORDER:
 		if (can_fault(vmf, PUD_SIZE, &pfn))
 			ret = vmf_insert_pfn_pud(vmf, pfn, vmf->flags & FAULT_FLAG_WRITE);
 		return ret;
+#endif
 
 	default:
 		return VM_FAULT_SIGBUS;
-- 
2.43.0

[PATCH 11/11] Drivers: hv: Kconfig: Add ARM64 support for MSHV_VTL

[Naman Jain]

Enable ARM64 support in MSHV_VTL Kconfig now that all the necessary
support is present.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
---
 drivers/hv/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
index 7937ac0cbd0f..393cef272590 100644
--- a/drivers/hv/Kconfig
+++ b/drivers/hv/Kconfig
@@ -87,7 +87,7 @@ config MSHV_ROOT
 
 config MSHV_VTL
 	tristate "Microsoft Hyper-V VTL driver"
-	depends on X86_64 && HYPERV_VTL_MODE
+	depends on (X86_64 || ARM64) && HYPERV_VTL_MODE
 	depends on HYPERV_VMBUS
 	# Mapping VTL0 memory to a userspace process in VTL2 is supported in OpenHCL.
 	# VTL2 for OpenHCL makes use of Huge Pages to improve performance on VMs,
-- 
2.43.0

Re: [PATCH 00/11] Drivers: hv: Add ARM64 support in mshv_vtl

[vdso]

> On 03/16/2026 5:12 AM  Naman Jain <namjain@linux.microsoft.com> wrote:
> 
>  
> The series intends to add support for ARM64 to mshv_vtl driver.
> For this, common Hyper-V code is refactored, necessary support is added,
> mshv_vtl_main.c is refactored and then finally support is added in
> Kconfig.

Hi Naman, Saurabh,

So awesome to see the ARM64 support for the VSM being upstreamed!!

Few of the patches carry my old Microsoft "Signed-off-by" tag,
and I really appreciate you folks very much kindly adding it
although the code appears to be a far more evolved and crisper
version of what it was back then!

Do feel free to drop my SOB from these few patches so the below SRB
doesn't look weird or as a conflict of interest - that is if you see
adding my below SRB to these few patches as a good option. It's been
2 years, and after 2 years who can really remember their code :D

For the series,
Reviewed-by: Roman Kisel <vdso@mailbox.org>

> 
> Based on commit 1f318b96cc84 ("Linux 7.0-rc3")
> 
> Naman Jain (11):
>   arch: arm64: Export arch_smp_send_reschedule for mshv_vtl module
>   Drivers: hv: Move hv_vp_assist_page to common files
>   Drivers: hv: Add support to setup percpu vmbus handler
>   Drivers: hv: Refactor mshv_vtl for ARM64 support to be added
>   drivers: hv: Export vmbus_interrupt for mshv_vtl module
>   Drivers: hv: Make sint vector architecture neutral in MSHV_VTL
>   arch: arm64: Add support for mshv_vtl_return_call
>   Drivers: hv: mshv_vtl: Move register page config to arch-specific
>     files
>   Drivers: hv: mshv_vtl: Let userspace do VSM configuration
>   Drivers: hv: Add support for arm64 in MSHV_VTL
>   Drivers: hv: Kconfig: Add ARM64 support for MSHV_VTL
> 
>  arch/arm64/hyperv/Makefile        |   1 +
>  arch/arm64/hyperv/hv_vtl.c        | 152 ++++++++++++++++++++++
>  arch/arm64/hyperv/mshyperv.c      |  13 ++
>  arch/arm64/include/asm/mshyperv.h |  28 ++++
>  arch/arm64/kernel/smp.c           |   1 +
>  arch/x86/hyperv/hv_init.c         |  88 +------------
>  arch/x86/hyperv/hv_vtl.c          | 130 +++++++++++++++++++
>  arch/x86/include/asm/mshyperv.h   |   8 +-
>  drivers/hv/Kconfig                |   2 +-
>  drivers/hv/hv_common.c            |  99 +++++++++++++++
>  drivers/hv/mshv.h                 |   8 --
>  drivers/hv/mshv_vtl_main.c        | 205 ++++--------------------------
>  drivers/hv/vmbus_drv.c            |   8 +-
>  include/asm-generic/mshyperv.h    |  49 +++++++
>  include/hyperv/hvgdk_mini.h       |   2 +
>  15 files changed, 505 insertions(+), 289 deletions(-)
>  create mode 100644 arch/arm64/hyperv/hv_vtl.c
> 
> 
> base-commit: 1f318b96cc84d7c2ab792fcc0bfd42a7ca890681
> prerequisite-patch-id: 24022ec1fb63bc20de8114eedf03c81bb1086e0e
> prerequisite-patch-id: 801f2588d5c6db4ceb9a6705a09e4649fab411b1
> prerequisite-patch-id: 581c834aa268f0c54120c6efbc1393fbd9893f49
> prerequisite-patch-id: b0b153807bab40860502c52e4a59297258ade0db
> prerequisite-patch-id: 2bff6accea80e7976c58d80d847cd33f260a3cb9
> prerequisite-patch-id: 296ffbc4f119a5b249bc9c840f84129f5c151139
> prerequisite-patch-id: 3b54d121145e743ac5184518df33a1812280ec96
> prerequisite-patch-id: 06fc5b37b23ee3f91a2c8c9b9c126fde290834f2
> prerequisite-patch-id: 6e8afed988309b03485f5538815ea29c8fa5b0a9
> prerequisite-patch-id: 4f1fb1b7e9cfa8a3b1c02fafecdbb432b74ee367
> prerequisite-patch-id: 49944347e0b2d93e72911a153979c567ebb7e66b
> prerequisite-patch-id: 6dec75498eeae6365d15ac12b5d0a3bd32e9f91c
> -- 
> 2.43.0

Re: [PATCH 00/11] Drivers: hv: Add ARM64 support in mshv_vtl

[Naman Jain]

On 3/17/2026 9:04 AM, vdso@mailbox.org wrote:
> 
>> On 03/16/2026 5:12 AM  Naman Jain <namjain@linux.microsoft.com> wrote:
>>
>>   
>> The series intends to add support for ARM64 to mshv_vtl driver.
>> For this, common Hyper-V code is refactored, necessary support is added,
>> mshv_vtl_main.c is refactored and then finally support is added in
>> Kconfig.
> 
> Hi Naman, Saurabh,
> 
> So awesome to see the ARM64 support for the VSM being upstreamed!!
> 
> Few of the patches carry my old Microsoft "Signed-off-by" tag,
> and I really appreciate you folks very much kindly adding it
> although the code appears to be a far more evolved and crisper
> version of what it was back then!
> 
> Do feel free to drop my SOB from these few patches so the below SRB
> doesn't look weird or as a conflict of interest - that is if you see
> adding my below SRB to these few patches as a good option. It's been
> 2 years, and after 2 years who can really remember their code :D
> 
> For the series,
> Reviewed-by: Roman Kisel <vdso@mailbox.org>



Thank you so much Roman for reviewing the changes. I think we can retain 
both the tags from you. I'll let the maintainers decide.

Regards,
Naman

RE: [PATCH 00/11] Drivers: hv: Add ARM64 support in mshv_vtl

[Michael Kelley]

From: Naman Jain <namjain@linux.microsoft.com> Sent: Monday, March 16, 2026 5:13 AM
> 
> The series intends to add support for ARM64 to mshv_vtl driver.
> For this, common Hyper-V code is refactored, necessary support is added,
> mshv_vtl_main.c is refactored and then finally support is added in
> Kconfig.
> 
> Based on commit 1f318b96cc84 ("Linux 7.0-rc3")

There's now an online LLM-based tool that is automatically reviewing
kernel patches. For this patch set, the results are here:

https://sashiko.dev/#/patchset/20260316121241.910764-1-namjain%40linux.microsoft.com

It has flagged several things that are worth checking, but I haven't
reviewed them to see if they are actually valid.

FWIW, the announcement about sashiko.dev is here:

https://lore.kernel.org/lkml/7ia4o6kmpj5s.fsf@castle.c.googlers.com/

Michael

> 
> Naman Jain (11):
>   arch: arm64: Export arch_smp_send_reschedule for mshv_vtl module
>   Drivers: hv: Move hv_vp_assist_page to common files
>   Drivers: hv: Add support to setup percpu vmbus handler
>   Drivers: hv: Refactor mshv_vtl for ARM64 support to be added
>   drivers: hv: Export vmbus_interrupt for mshv_vtl module
>   Drivers: hv: Make sint vector architecture neutral in MSHV_VTL
>   arch: arm64: Add support for mshv_vtl_return_call
>   Drivers: hv: mshv_vtl: Move register page config to arch-specific
>     files
>   Drivers: hv: mshv_vtl: Let userspace do VSM configuration
>   Drivers: hv: Add support for arm64 in MSHV_VTL
>   Drivers: hv: Kconfig: Add ARM64 support for MSHV_VTL
> 
>  arch/arm64/hyperv/Makefile        |   1 +
>  arch/arm64/hyperv/hv_vtl.c        | 152 ++++++++++++++++++++++
>  arch/arm64/hyperv/mshyperv.c      |  13 ++
>  arch/arm64/include/asm/mshyperv.h |  28 ++++
>  arch/arm64/kernel/smp.c           |   1 +
>  arch/x86/hyperv/hv_init.c         |  88 +------------
>  arch/x86/hyperv/hv_vtl.c          | 130 +++++++++++++++++++
>  arch/x86/include/asm/mshyperv.h   |   8 +-
>  drivers/hv/Kconfig                |   2 +-
>  drivers/hv/hv_common.c            |  99 +++++++++++++++
>  drivers/hv/mshv.h                 |   8 --
>  drivers/hv/mshv_vtl_main.c        | 205 ++++--------------------------
>  drivers/hv/vmbus_drv.c            |   8 +-
>  include/asm-generic/mshyperv.h    |  49 +++++++
>  include/hyperv/hvgdk_mini.h       |   2 +
>  15 files changed, 505 insertions(+), 289 deletions(-)
>  create mode 100644 arch/arm64/hyperv/hv_vtl.c
> 
> 
> base-commit: 1f318b96cc84d7c2ab792fcc0bfd42a7ca890681
> prerequisite-patch-id: 24022ec1fb63bc20de8114eedf03c81bb1086e0e
> prerequisite-patch-id: 801f2588d5c6db4ceb9a6705a09e4649fab411b1
> prerequisite-patch-id: 581c834aa268f0c54120c6efbc1393fbd9893f49
> prerequisite-patch-id: b0b153807bab40860502c52e4a59297258ade0db
> prerequisite-patch-id: 2bff6accea80e7976c58d80d847cd33f260a3cb9
> prerequisite-patch-id: 296ffbc4f119a5b249bc9c840f84129f5c151139
> prerequisite-patch-id: 3b54d121145e743ac5184518df33a1812280ec96
> prerequisite-patch-id: 06fc5b37b23ee3f91a2c8c9b9c126fde290834f2
> prerequisite-patch-id: 6e8afed988309b03485f5538815ea29c8fa5b0a9
> prerequisite-patch-id: 4f1fb1b7e9cfa8a3b1c02fafecdbb432b74ee367
> prerequisite-patch-id: 49944347e0b2d93e72911a153979c567ebb7e66b
> prerequisite-patch-id: 6dec75498eeae6365d15ac12b5d0a3bd32e9f91c
> --
> 2.43.0
> 

Re: [PATCH 00/11] Drivers: hv: Add ARM64 support in mshv_vtl

[Naman Jain]

On 3/18/2026 3:33 AM, Michael Kelley wrote:
> From: Naman Jain <namjain@linux.microsoft.com> Sent: Monday, March 16, 2026 5:13 AM
>>
>> The series intends to add support for ARM64 to mshv_vtl driver.
>> For this, common Hyper-V code is refactored, necessary support is added,
>> mshv_vtl_main.c is refactored and then finally support is added in
>> Kconfig.
>>
>> Based on commit 1f318b96cc84 ("Linux 7.0-rc3")
> 
> There's now an online LLM-based tool that is automatically reviewing
> kernel patches. For this patch set, the results are here:
> 
> https://sashiko.dev/#/patchset/20260316121241.910764-1-namjain%40linux.microsoft.com
> 
> It has flagged several things that are worth checking, but I haven't
> reviewed them to see if they are actually valid.
> 
> FWIW, the announcement about sashiko.dev is here:
> 
> https://lore.kernel.org/lkml/7ia4o6kmpj5s.fsf@castle.c.googlers.com/
> 
> Michael


Thanks for sharing Michael,
I'll check it out and do the needful.

Regards,
Naman