[PATCH hyperv-next v8 00/11] arm64: hyperv: Support Virtual Trust Level Boot

[PATCH hyperv-next v8 00/11] arm64: hyperv: Support Virtual Trust Level Boot

[Roman Kisel]

This patch set allows the Hyper-V code to boot on ARM64 inside a Virtual Trust
Level. These levels are a part of the Virtual Secure Mode documented in the
Top-Level Functional Specification available at
https://learn.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/vsm.

The OpenHCL paravisor https://github.com/microsoft/openvmm/tree/main/openhcl
can serve as a practical application of these patches on ARM64.

For validation, I built kernels for the {x86_64, ARM64} x {VTL0, VTL2} set with
a small initrd embedded into the kernel and booted VMs managed by Hyper-V and
OpenVMM off of that.

Starting from V5, the patch series includes a non-functional change to KVM on
arm64 which I tested as well.

[V8]
    - Use the Linux derfined macro __ASSEMBLY__ instead of the gcc's pre-defined
      macro __ASSEMBLER__ to follow the kernel coding style.
      ** Thank you, Marc! **

[V7]
    https://lore.kernel.org/linux-hyperv/20250407201336.66913-1-romank@linux.microsoft.com/
    - Used another approach not to increase the number of warnings produced when
      building with CHECK_ENDIAN.
      ** Thank you, Arnd! **

     - Adjusted the function parameter formatting to match the rest of the code.
      ** Thank you, Bjorn! **

    - Removed the now unused local variable.
      ** Thank you, kernel robot! **

    - Fixed the description in the VMBus DT binding patch.
      ** Thank you, Krzysztof! **

    - Adjusted the function names and comments to better reflect what they do,
      used the suggested approach to handling UUIDs to make code more readable
      and maintainable on big-endian.
    - Replaced ifdeffery with a stub function to make the code more readable.
      ** Thank you, Mark! **

    - Fixed the Kconfig not to build the VTL mode code on 32-bit kernels.
      ** Thank you, Michael! **

    - Fixed the indentation and the comment style.
      ** Thank you, Rafael! **

[V6]
    https://lore.kernel.org/linux-hyperv/20250315001931.631210-1-romank@linux.microsoft.com/
    - Use more intuitive Kconfig update.
    - Remove ifdef for getting IRQ number
    ** Thank you, Arnd! **

    - Simplify code for finding the parent IRQ domain.
    ** Thank you, Bjorn! **

    - Remove a superfluous check.
    ** Thank you, Dan! **

    - Make the commit title and descrtiption legible.
    - Don't set additionalProperties to true.
    ** Thank you, Krzysztof! **

    - Fix spelling in the commit title and description.
    - Trade-offs for options in Kconfig.
    - Export the new symbol as hyperv-pci can be built as a module.
    ** Thank you, Michael! **

    - Simplify code for getting IRQ number.
    ** Thank you, Rob! **

    - Add comment to clarify when running in VTL mode is reported.
    ** Thank you, Wei! **

[V5]
  https://lore.kernel.org/linux-hyperv/20250307220304.247725-1-romank@linux.microsoft.com/
    - Provide and use a common SMCCC-based infra for the arm64 hypervisor guests
      to detect hypervisor presence.
    ** Thank you, Arnd! **

    - Fix line wraps to follow the rest of the code.
    - Open-code getting IRQ domain parent in the ACPI case to make the code
      better.
    ** Thank you, Bjorn! **

    - Test the binding with the latest dtschema.
    - Clean up the commit title and description.
    - Use proper defines for known constants.
    ** Thank you, Krzysztof! **

    - Extend comment on why ACPI v6 is checked for.
    - Reorder patches to make sure that even with partial series application
      the compilation succeeds.
    - Report VTL the kernel runs in.
    - Use "X86_64" in Kconfig rather than "X86".
    - Extract a non-functional change for hv_get_vmbus_root_device() into
      a separate patch.
    ** Thank you, Michael! **

[V4]
    https://lore.kernel.org/linux-hyperv/20250212014321.1108840-1-romank@linux.microsoft.com/
    - Fixed wording to match acronyms defined in the "Terms and Abbreviations"
      section of the SMCCC specification throughout the patch series.
      **Thank you, Michael!**

    - Replaced the hypervisor ID containing ASCII with an UUID as
      required by the specification.
      **Thank you, Michael!**

    - Added an explicit check for `SMCCC_RET_NOT_SUPPORTED` when discovering the
      hypervisor presence to make the backward compatibility obvious.
      **Thank you, Saurabh!**

    - Split the fix for `get_vtl(void)` out to make it easier to backport.
    - Refactored the configuration options as requested to eliminate the risk
      of building non-functional kernels with randomly selected options.
      **Thank you, Michael!**

    - Refactored the changes not to introduce an additional file with
      a one-line function.
      **Thank you, Wei!**

    - Fixed change description for the VMBus DeviceTree changes, used
      `scripts/get_maintainers.pl` on the latest kernel to get the up-to-date list
      of maintainers as requested.
      **Thank you, Krzysztof!**

    - Removed the added (paranoidal+superfluous) checks for DMA coherence in the
      VMBus driver and instead relied on the DMA and the OF subsystem code.
      **Thank you, Arnd, Krzysztof, Michael!**

    - Used another set of APIs for discovering the hardware interrupt number
      in the VMBus driver to be able to build the driver as a module.
      **Thank you, Michael, Saurabh!**

    - Renamed the newly introduced `get_vmbus_root_device(void)` function to
      `hv_get_vmbus_root_device(void)` as requested.
      **Thank you, Wei!**

    - Applied the suggested small-scale refactoring to simplify changes to the Hyper-V
      PCI driver. Taking the offered liberty of doing the large scale refactoring
      in another patch series.
      **Thank you, Michael!**

    - Added a fix for the issue discovered internally where the CPU would not
      get the interrupt from a PCI device attached to VTL2 as the shared peripheral
      interrupt number (SPI) was not offset by 32 (the first valid SPI number).
      **Thank you, Brian!**

[V3]
    https://lore.kernel.org/lkml/20240726225910.1912537-1-romank@linux.microsoft.com/
    - Employed the SMCCC function recently implemented in the Microsoft Hyper-V
      hypervisor to detect running on Hyper-V/arm64. No dependence on ACPI/DT is
      needed anymore although the source code still falls back to ACPI as the new
      hypervisor might be available only in the Windows Insiders channel just
      yet.
    - As a part of the above, refactored detecting the hypervisor via ACPI FADT.
    - There was a suggestion to explore whether it is feasible or not to express
      that ACPI must be absent for the VTL mode and present for the regular guests
      in the Hyper-V Kconfig file.
      My current conclusion is that this will require refactoring in many places.
      That becomes especially convoluted on x86_64 due to the MSI and APIC
      dependencies. I'd ask to let us tackle that in another patch series (or chalk
      up to nice-have's rather than fires to put out) to separate concerns and
      decrease chances of breakage.
    - While refactoring `get_vtl(void)` and the related code, fixed the hypercall
      output address not to overlap with the input as the Hyper-V TLFS mandates:
      "The input and output parameter lists cannot overlap or cross page boundaries."
      See https://learn.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/hypercall-interface
      for more.
      Some might argue that should've been a topic for a separate patch series;
      I'd counter that the change is well-contained (one line), has no dependencies,
      and makes the code legal.
    - Made the VTL boot code (c)leaner as was suggested.
    - Set DMA cache coherency for the VMBus.
    - Updated DT bindings in the VMBus documentation (separated out into a new patch).
    - Fixed `vmbus_set_irq` to use the API that works both for the ACPI and OF.
    - Reworked setting up the vPCI MSI IRQ domain in the non-ACPI case. The logic
      looks a bit fiddly/ad-hoc as I couldn't find the API that would fit the bill.
      Added comments to explain myself.

[V2]
    https://lore.kernel.org/all/20240514224508.212318-1-romank@linux.microsoft.com/
    - Decreased number of #ifdef's
    - Updated the wording in the commit messages to adhere to the guidlines
    - Sending to the correct set of maintainers and mail lists

[V1]
    https://lore.kernel.org/all/20240510160602.1311352-1-romank@linux.microsoft.com/

Roman Kisel (11):
  arm64: kvm, smccc: Introduce and use API for getting hypervisor UUID
  arm64: hyperv: Use SMCCC to detect hypervisor presence
  Drivers: hv: Enable VTL mode for arm64
  Drivers: hv: Provide arch-neutral implementation of get_vtl()
  arm64: hyperv: Initialize the Virtual Trust Level field
  arm64, x86: hyperv: Report the VTL the system boots in
  dt-bindings: microsoft,vmbus: Add interrupt and DMA coherence
    properties
  Drivers: hv: vmbus: Get the IRQ number from DeviceTree
  Drivers: hv: vmbus: Introduce hv_get_vmbus_root_device()
  ACPI: irq: Introduce acpi_get_gsi_dispatcher()
  PCI: hv: Get vPCI MSI IRQ domain from DeviceTree

 .../bindings/bus/microsoft,vmbus.yaml         | 16 ++++-
 arch/arm64/hyperv/mshyperv.c                  | 53 ++++++++++++--
 arch/arm64/kvm/hypercalls.c                   | 10 +--
 arch/x86/hyperv/hv_init.c                     | 34 ---------
 arch/x86/hyperv/hv_vtl.c                      |  7 +-
 drivers/acpi/irq.c                            | 16 ++++-
 drivers/firmware/smccc/kvm_guest.c            | 10 +--
 drivers/firmware/smccc/smccc.c                | 17 +++++
 drivers/hv/Kconfig                            |  6 +-
 drivers/hv/hv_common.c                        | 31 ++++++++
 drivers/hv/vmbus_drv.c                        | 53 +++++++++++---
 drivers/pci/controller/pci-hyperv.c           | 72 +++++++++++++++++--
 include/asm-generic/mshyperv.h                |  6 ++
 include/hyperv/hvgdk_mini.h                   |  2 +-
 include/linux/acpi.h                          |  5 +-
 include/linux/arm-smccc.h                     | 64 +++++++++++++++--
 include/linux/hyperv.h                        |  2 +
 17 files changed, 325 insertions(+), 79 deletions(-)


base-commit: 628cc040b3a2980df6032766e8ef0688e981ab95
-- 
2.43.0

[PATCH hyperv-next v8 01/11] arm64: kvm, smccc: Introduce and use API for getting hypervisor UUID

[Roman Kisel]

The KVM/arm64 uses SMCCC to detect hypervisor presence. That code is
private, and it follows the SMCCC specification. Other existing and
emerging hypervisor guest implementations can and should use that
standard approach as well.

Factor out a common infrastructure that the guests can use, update KVM
to employ the new API. The central notion of the SMCCC method is the
UUID of the hypervisor, and the new API follows that.

No functional changes. Validated with a KVM/arm64 guest.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
---
 arch/arm64/kvm/hypercalls.c        | 10 +++--
 drivers/firmware/smccc/kvm_guest.c | 10 +----
 drivers/firmware/smccc/smccc.c     | 17 ++++++++
 include/linux/arm-smccc.h          | 64 ++++++++++++++++++++++++++++--
 4 files changed, 85 insertions(+), 16 deletions(-)

diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index 27ce4cb44904..e641cb2b47d7 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -268,6 +268,7 @@ int kvm_smccc_call_handler(struct kvm_vcpu *vcpu)
 	u32 feature;
 	u8 action;
 	gpa_t gpa;
+	uuid_t uuid;
 
 	action = kvm_smccc_get_action(vcpu, func_id);
 	switch (action) {
@@ -353,10 +354,11 @@ int kvm_smccc_call_handler(struct kvm_vcpu *vcpu)
 			val[0] = gpa;
 		break;
 	case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
-		val[0] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_0;
-		val[1] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_1;
-		val[2] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_2;
-		val[3] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_3;
+		uuid = ARM_SMCCC_VENDOR_HYP_UID_KVM;
+		val[0] = smccc_uuid_to_reg(&uuid, 0);
+		val[1] = smccc_uuid_to_reg(&uuid, 1);
+		val[2] = smccc_uuid_to_reg(&uuid, 2);
+		val[3] = smccc_uuid_to_reg(&uuid, 3);
 		break;
 	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
 		val[0] = smccc_feat->vendor_hyp_bmap;
diff --git a/drivers/firmware/smccc/kvm_guest.c b/drivers/firmware/smccc/kvm_guest.c
index f3319be20b36..87f910887d61 100644
--- a/drivers/firmware/smccc/kvm_guest.c
+++ b/drivers/firmware/smccc/kvm_guest.c
@@ -14,17 +14,11 @@ static DECLARE_BITMAP(__kvm_arm_hyp_services, ARM_SMCCC_KVM_NUM_FUNCS) __ro_afte
 
 void __init kvm_init_hyp_services(void)
 {
+	uuid_t kvm_uuid = ARM_SMCCC_VENDOR_HYP_UID_KVM;
 	struct arm_smccc_res res;
 	u32 val[4];
 
-	if (arm_smccc_1_1_get_conduit() != SMCCC_CONDUIT_HVC)
-		return;
-
-	arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, &res);
-	if (res.a0 != ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_0 ||
-	    res.a1 != ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_1 ||
-	    res.a2 != ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_2 ||
-	    res.a3 != ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_3)
+	if (!arm_smccc_hypervisor_has_uuid(&kvm_uuid))
 		return;
 
 	memset(&res, 0, sizeof(res));
diff --git a/drivers/firmware/smccc/smccc.c b/drivers/firmware/smccc/smccc.c
index a74600d9f2d7..cd65b434dc6e 100644
--- a/drivers/firmware/smccc/smccc.c
+++ b/drivers/firmware/smccc/smccc.c
@@ -67,6 +67,23 @@ s32 arm_smccc_get_soc_id_revision(void)
 }
 EXPORT_SYMBOL_GPL(arm_smccc_get_soc_id_revision);
 
+bool arm_smccc_hypervisor_has_uuid(const uuid_t *hyp_uuid)
+{
+	struct arm_smccc_res res = {};
+	uuid_t uuid;
+
+	if (arm_smccc_1_1_get_conduit() != SMCCC_CONDUIT_HVC)
+		return false;
+
+	arm_smccc_1_1_hvc(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, &res);
+	if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
+		return false;
+
+	uuid = smccc_res_to_uuid(res.a0, res.a1, res.a2, res.a3);
+	return uuid_equal(&uuid, hyp_uuid);
+}
+EXPORT_SYMBOL_GPL(arm_smccc_hypervisor_has_uuid);
+
 static int __init smccc_devices_init(void)
 {
 	struct platform_device *pdev;
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index 67f6fdf2e7cd..4bb38f0e3fe2 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -7,6 +7,11 @@
 
 #include <linux/args.h>
 #include <linux/init.h>
+
+#ifndef __ASSEMBLY__
+#include <linux/uuid.h>
+#endif
+
 #include <uapi/linux/const.h>
 
 /*
@@ -107,10 +112,10 @@
 			   ARM_SMCCC_FUNC_QUERY_CALL_UID)
 
 /* KVM UID value: 28b46fb6-2ec5-11e9-a9ca-4b564d003a74 */
-#define ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_0	0xb66fb428U
-#define ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_1	0xe911c52eU
-#define ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_2	0x564bcaa9U
-#define ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_3	0x743a004dU
+#define ARM_SMCCC_VENDOR_HYP_UID_KVM UUID_INIT(\
+	0xb66fb428, 0xc52e, 0xe911, \
+	0xa9, 0xca, 0x4b, 0x56, \
+	0x4d, 0x00, 0x3a, 0x74)
 
 /* KVM "vendor specific" services */
 #define ARM_SMCCC_KVM_FUNC_FEATURES		0
@@ -333,6 +338,57 @@ s32 arm_smccc_get_soc_id_version(void);
  */
 s32 arm_smccc_get_soc_id_revision(void);
 
+#ifndef __ASSEMBLY__
+
+/*
+ * Returns whether a specific hypervisor UUID is advertised for the
+ * Vendor Specific Hypervisor Service range.
+ */
+bool arm_smccc_hypervisor_has_uuid(const uuid_t *uuid);
+
+static inline uuid_t smccc_res_to_uuid(u32 r0, u32 r1, u32 r2, u32 r3)
+{
+	uuid_t uuid = {
+		.b = {
+			[0]  = (r0 >> 0)  & 0xff,
+			[1]  = (r0 >> 8)  & 0xff,
+			[2]  = (r0 >> 16) & 0xff,
+			[3]  = (r0 >> 24) & 0xff,
+
+			[4]  = (r1 >> 0)  & 0xff,
+			[5]  = (r1 >> 8)  & 0xff,
+			[6]  = (r1 >> 16) & 0xff,
+			[7]  = (r1 >> 24) & 0xff,
+
+			[8]  = (r2 >> 0)  & 0xff,
+			[9]  = (r2 >> 8)  & 0xff,
+			[10] = (r2 >> 16) & 0xff,
+			[11] = (r2 >> 24) & 0xff,
+
+			[12] = (r3 >> 0)  & 0xff,
+			[13] = (r3 >> 8)  & 0xff,
+			[14] = (r3 >> 16) & 0xff,
+			[15] = (r3 >> 24) & 0xff,
+		},
+	};
+
+	return uuid;
+}
+
+static inline u32 smccc_uuid_to_reg(const uuid_t *uuid, int reg)
+{
+	u32 val = 0;
+
+	val |= (u32)(uuid->b[4 * reg + 0] << 0);
+	val |= (u32)(uuid->b[4 * reg + 1] << 8);
+	val |= (u32)(uuid->b[4 * reg + 2] << 16);
+	val |= (u32)(uuid->b[4 * reg + 3] << 24);
+
+	return val;
+}
+
+#endif /* !__ASSEMBLY__ */
+
 /**
  * struct arm_smccc_res - Result from SMC/HVC call
  * @a0-a3 result values from registers 0 to 3
-- 
2.43.0

[PATCH hyperv-next v8 02/11] arm64: hyperv: Use SMCCC to detect hypervisor presence

[Roman Kisel]

The arm64 Hyper-V startup path relies on ACPI to detect
running under a Hyper-V compatible hypervisor. That
doesn't work on non-ACPI systems.

Hoist the ACPI detection logic into a separate function. Then
use the vendor-specific hypervisor service call (implemented
recently in Hyper-V) via SMCCC in the non-ACPI case.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
---
 arch/arm64/hyperv/mshyperv.c | 50 ++++++++++++++++++++++++++++++++----
 1 file changed, 45 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
index 4e27cc29c79e..21458b6338aa 100644
--- a/arch/arm64/hyperv/mshyperv.c
+++ b/arch/arm64/hyperv/mshyperv.c
@@ -28,6 +28,48 @@ int hv_get_hypervisor_version(union hv_hypervisor_version_info *info)
 }
 EXPORT_SYMBOL_GPL(hv_get_hypervisor_version);
 
+#ifdef CONFIG_ACPI
+
+static bool __init hyperv_detect_via_acpi(void)
+{
+	if (acpi_disabled)
+		return false;
+	/*
+	 * Hypervisor ID is only available in ACPI v6+, and the
+	 * structure layout was extended in v6 to accommodate that
+	 * new field.
+	 *
+	 * At the very minimum, this check makes sure not to read
+	 * past the FADT structure.
+	 *
+	 * It is also needed to catch running in some unknown
+	 * non-Hyper-V environment that has ACPI 5.x or less.
+	 * In such a case, it can't be Hyper-V.
+	 */
+	if (acpi_gbl_FADT.header.revision < 6)
+		return false;
+	return strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8) == 0;
+}
+
+#else
+
+static bool __init hyperv_detect_via_acpi(void)
+{
+	return false;
+}
+
+#endif
+
+static bool __init hyperv_detect_via_smccc(void)
+{
+	uuid_t hyperv_uuid = UUID_INIT(
+		0x58ba324d, 0x6447, 0x24cd,
+		0x75, 0x6c, 0xef, 0x8e,
+		0x24, 0x70, 0x59, 0x16);
+
+	return arm_smccc_hypervisor_has_uuid(&hyperv_uuid);
+}
+
 static int __init hyperv_init(void)
 {
 	struct hv_get_vp_registers_output	result;
@@ -36,13 +78,11 @@ static int __init hyperv_init(void)
 
 	/*
 	 * Allow for a kernel built with CONFIG_HYPERV to be running in
-	 * a non-Hyper-V environment, including on DT instead of ACPI.
+	 * a non-Hyper-V environment.
+	 *
 	 * In such cases, do nothing and return success.
 	 */
-	if (acpi_disabled)
-		return 0;
-
-	if (strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8))
+	if (!hyperv_detect_via_acpi() && !hyperv_detect_via_smccc())
 		return 0;
 
 	/* Setup the guest ID */
-- 
2.43.0

[PATCH hyperv-next v8 03/11] Drivers: hv: Enable VTL mode for arm64

[Roman Kisel]

Kconfig dependencies for arm64 guests on Hyper-V require that be
ACPI enabled, and limit VTL mode to x86/x64. To enable VTL mode
on arm64 as well, update the dependencies. Since VTL mode requires
DeviceTree instead of ACPI, don’t require arm64 guests on Hyper-V
to have ACPI unconditionally.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
---
 drivers/hv/Kconfig | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
index 6c1416167bd2..eefa0b559b73 100644
--- a/drivers/hv/Kconfig
+++ b/drivers/hv/Kconfig
@@ -5,7 +5,7 @@ menu "Microsoft Hyper-V guest support"
 config HYPERV
 	tristate "Microsoft Hyper-V client drivers"
 	depends on (X86 && X86_LOCAL_APIC && HYPERVISOR_GUEST) \
-		|| (ACPI && ARM64 && !CPU_BIG_ENDIAN)
+		|| (ARM64 && !CPU_BIG_ENDIAN)
 	select PARAVIRT
 	select X86_HV_CALLBACK_VECTOR if X86
 	select OF_EARLY_FLATTREE if OF
@@ -15,7 +15,7 @@ config HYPERV
 
 config HYPERV_VTL_MODE
 	bool "Enable Linux to boot in VTL context"
-	depends on X86_64 && HYPERV
+	depends on (X86_64 || ARM64) && HYPERV
 	depends on SMP
 	default n
 	help
@@ -31,7 +31,7 @@ config HYPERV_VTL_MODE
 
 	  Select this option to build a Linux kernel to run at a VTL other than
 	  the normal VTL0, which currently is only VTL2.  This option
-	  initializes the x86 platform for VTL2, and adds the ability to boot
+	  initializes the kernel to run in VTL2, and adds the ability to boot
 	  secondary CPUs directly into 64-bit context as required for VTLs other
 	  than 0.  A kernel built with this option must run at VTL2, and will
 	  not run as a normal guest.
-- 
2.43.0

[PATCH hyperv-next v8 04/11] Drivers: hv: Provide arch-neutral implementation of get_vtl()

[Roman Kisel]

To run in the VTL mode, Hyper-V drivers have to know what
VTL the system boots in, and the arm64/hyperv code does not
have the means to compute that.

Refactor the code to hoist the function that detects VTL,
make it arch-neutral to be able to employ it to get the VTL
on arm64.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Tianyu Lan <tiala@microsoft.com>
---
 arch/x86/hyperv/hv_init.c      | 34 ----------------------------------
 drivers/hv/hv_common.c         | 31 +++++++++++++++++++++++++++++++
 include/asm-generic/mshyperv.h |  6 ++++++
 include/hyperv/hvgdk_mini.h    |  2 +-
 4 files changed, 38 insertions(+), 35 deletions(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index ddeb40930bc8..3b569291dfed 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -390,40 +390,6 @@ static void __init hv_stimer_setup_percpu_clockev(void)
 		old_setup_percpu_clockev();
 }
 
-#if IS_ENABLED(CONFIG_HYPERV_VTL_MODE)
-static u8 __init get_vtl(void)
-{
-	u64 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_REGISTERS;
-	struct hv_input_get_vp_registers *input;
-	struct hv_output_get_vp_registers *output;
-	unsigned long flags;
-	u64 ret;
-
-	local_irq_save(flags);
-	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
-	output = *this_cpu_ptr(hyperv_pcpu_output_arg);
-
-	memset(input, 0, struct_size(input, names, 1));
-	input->partition_id = HV_PARTITION_ID_SELF;
-	input->vp_index = HV_VP_INDEX_SELF;
-	input->input_vtl.as_uint8 = 0;
-	input->names[0] = HV_REGISTER_VSM_VP_STATUS;
-
-	ret = hv_do_hypercall(control, input, output);
-	if (hv_result_success(ret)) {
-		ret = output->values[0].reg8 & HV_X64_VTL_MASK;
-	} else {
-		pr_err("Failed to get VTL(error: %lld) exiting...\n", ret);
-		BUG();
-	}
-
-	local_irq_restore(flags);
-	return ret;
-}
-#else
-static inline u8 get_vtl(void) { return 0; }
-#endif
-
 /*
  * This function is to be invoked early in the boot sequence after the
  * hypervisor has been detected.
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index b3b11be11650..1ece6721c486 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -317,6 +317,37 @@ void __init hv_get_partition_id(void)
 		pr_err("Hyper-V: failed to get partition ID: %#x\n",
 		       hv_result(status));
 }
+#if IS_ENABLED(CONFIG_HYPERV_VTL_MODE)
+u8 __init get_vtl(void)
+{
+	u64 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_REGISTERS;
+	struct hv_input_get_vp_registers *input;
+	struct hv_output_get_vp_registers *output;
+	unsigned long flags;
+	u64 ret;
+
+	local_irq_save(flags);
+	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	output = *this_cpu_ptr(hyperv_pcpu_output_arg);
+
+	memset(input, 0, struct_size(input, names, 1));
+	input->partition_id = HV_PARTITION_ID_SELF;
+	input->vp_index = HV_VP_INDEX_SELF;
+	input->input_vtl.as_uint8 = 0;
+	input->names[0] = HV_REGISTER_VSM_VP_STATUS;
+
+	ret = hv_do_hypercall(control, input, output);
+	if (hv_result_success(ret)) {
+		ret = output->values[0].reg8 & HV_VTL_MASK;
+	} else {
+		pr_err("Failed to get VTL(error: %lld) exiting...\n", ret);
+		BUG();
+	}
+
+	local_irq_restore(flags);
+	return ret;
+}
+#endif
 
 int __init hv_common_init(void)
 {
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index ccccb1cbf7df..6c51a25ed7b5 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -378,4 +378,10 @@ static inline int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u3
 }
 #endif /* CONFIG_MSHV_ROOT */
 
+#if IS_ENABLED(CONFIG_HYPERV_VTL_MODE)
+u8 __init get_vtl(void);
+#else
+static inline u8 get_vtl(void) { return 0; }
+#endif
+
 #endif
diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h
index abf0bd76e370..cf0923dc727d 100644
--- a/include/hyperv/hvgdk_mini.h
+++ b/include/hyperv/hvgdk_mini.h
@@ -1228,7 +1228,7 @@ struct hv_send_ipi {	 /* HV_INPUT_SEND_SYNTHETIC_CLUSTER_IPI */
 	u64 cpu_mask;
 } __packed;
 
-#define	HV_X64_VTL_MASK			GENMASK(3, 0)
+#define	HV_VTL_MASK			GENMASK(3, 0)
 
 /* Hyper-V memory host visibility */
 enum hv_mem_host_visibility {
-- 
2.43.0

[PATCH hyperv-next v8 05/11] arm64: hyperv: Initialize the Virtual Trust Level field

[Roman Kisel]

Various parts of the hyperv code need to know what VTL
the kernel runs at, most notably VMBus needs that to
establish communication with the host.

Initialize the Virtual Trust Level field to enable
booting in the Virtual Trust Level.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
---
 arch/arm64/hyperv/mshyperv.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
index 21458b6338aa..43f422a7ef34 100644
--- a/arch/arm64/hyperv/mshyperv.c
+++ b/arch/arm64/hyperv/mshyperv.c
@@ -117,6 +117,7 @@ static int __init hyperv_init(void)
 
 	if (ms_hyperv.priv_high & HV_ACCESS_PARTITION_ID)
 		hv_get_partition_id();
+	ms_hyperv.vtl = get_vtl();
 
 	ms_hyperv_late_init();
 
-- 
2.43.0

[PATCH hyperv-next v8 06/11] arm64, x86: hyperv: Report the VTL the system boots in

[Roman Kisel]

The hyperv guest code might run in various Virtual Trust Levels.

Report the level when the kernel boots in the non-default (0)
one.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
---
 arch/arm64/hyperv/mshyperv.c | 2 ++
 arch/x86/hyperv/hv_vtl.c     | 7 ++++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
index 43f422a7ef34..4fdc26ade1d7 100644
--- a/arch/arm64/hyperv/mshyperv.c
+++ b/arch/arm64/hyperv/mshyperv.c
@@ -118,6 +118,8 @@ static int __init hyperv_init(void)
 	if (ms_hyperv.priv_high & HV_ACCESS_PARTITION_ID)
 		hv_get_partition_id();
 	ms_hyperv.vtl = get_vtl();
+	if (ms_hyperv.vtl > 0) /* non default VTL */
+		pr_info("Linux runs in Hyper-V Virtual Trust Level %d\n", ms_hyperv.vtl);
 
 	ms_hyperv_late_init();
 
diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c
index 582fe820e29c..038c896fdd60 100644
--- a/arch/x86/hyperv/hv_vtl.c
+++ b/arch/x86/hyperv/hv_vtl.c
@@ -55,7 +55,12 @@ static void  __noreturn hv_vtl_restart(char __maybe_unused *cmd)
 
 void __init hv_vtl_init_platform(void)
 {
-	pr_info("Linux runs in Hyper-V Virtual Trust Level\n");
+	/*
+	 * This function is a no-op if the VTL mode is not enabled.
+	 * If it is, this function runs if and only the kernel boots in
+	 * VTL2 which the x86 hv initialization path makes sure of.
+	 */
+	pr_info("Linux runs in Hyper-V Virtual Trust Level %d\n", ms_hyperv.vtl);
 
 	x86_platform.realmode_reserve = x86_init_noop;
 	x86_platform.realmode_init = x86_init_noop;
-- 
2.43.0

[PATCH hyperv-next v8 07/11] dt-bindings: microsoft,vmbus: Add interrupt and DMA coherence properties

[Roman Kisel]

To boot in the VTL mode, VMBus on arm64 needs interrupt description
which the binding documentation lacks. The transactions on the bus are
DMA coherent which is not mentioned as well.

Add the interrupt property and the DMA coherence property to the VMBus
binding. Update the example to match that. Fix typos.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---
 .../devicetree/bindings/bus/microsoft,vmbus.yaml | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/bus/microsoft,vmbus.yaml b/Documentation/devicetree/bindings/bus/microsoft,vmbus.yaml
index a8d40c766dcd..0bea4f5287ce 100644
--- a/Documentation/devicetree/bindings/bus/microsoft,vmbus.yaml
+++ b/Documentation/devicetree/bindings/bus/microsoft,vmbus.yaml
@@ -10,8 +10,8 @@ maintainers:
   - Saurabh Sengar <ssengar@linux.microsoft.com>
 
 description:
-  VMBus is a software bus that implement the protocols for communication
-  between the root or host OS and guest OSs (virtual machines).
+  VMBus is a software bus that implements the protocols for communication
+  between the root or host OS and guest OS'es (virtual machines).
 
 properties:
   compatible:
@@ -25,9 +25,16 @@ properties:
   '#size-cells':
     const: 1
 
+  dma-coherent: true
+
+  interrupts:
+    maxItems: 1
+    description: Interrupt is used to report a message from the host.
+
 required:
   - compatible
   - ranges
+  - interrupts
   - '#address-cells'
   - '#size-cells'
 
@@ -35,6 +42,8 @@ additionalProperties: false
 
 examples:
   - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
     soc {
         #address-cells = <2>;
         #size-cells = <1>;
@@ -49,6 +58,9 @@ examples:
                 #address-cells = <2>;
                 #size-cells = <1>;
                 ranges = <0x0f 0xf0000000 0x0f 0xf0000000 0x10000000>;
+                dma-coherent;
+                interrupt-parent = <&gic>;
+                interrupts = <GIC_PPI 2 IRQ_TYPE_EDGE_RISING>;
             };
         };
     };
-- 
2.43.0

[PATCH hyperv-next v8 08/11] Drivers: hv: vmbus: Get the IRQ number from DeviceTree

[Roman Kisel]

The VMBus driver uses ACPI for interrupt assignment on
arm64 hence it won't function in the VTL mode where only
DeviceTree can be used.

Update the VMBus driver to discover interrupt configuration
from DT.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
---
 drivers/hv/vmbus_drv.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 22afebfc28ff..e8f2c3e92d1f 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -2345,6 +2345,31 @@ static int vmbus_acpi_add(struct platform_device *pdev)
 }
 #endif
 
+static int vmbus_set_irq(struct platform_device *pdev)
+{
+	struct irq_data *data;
+	int irq;
+	irq_hw_number_t hwirq;
+
+	irq = platform_get_irq(pdev, 0);
+	/* platform_get_irq() may not return 0. */
+	if (irq < 0)
+		return irq;
+
+	data = irq_get_irq_data(irq);
+	if (!data) {
+		pr_err("No interrupt data for VMBus virq %d\n", irq);
+		return -ENODEV;
+	}
+	hwirq = irqd_to_hwirq(data);
+
+	vmbus_irq = irq;
+	vmbus_interrupt = hwirq;
+	pr_debug("VMBus virq %d, hwirq %d\n", vmbus_irq, vmbus_interrupt);
+
+	return 0;
+}
+
 static int vmbus_device_add(struct platform_device *pdev)
 {
 	struct resource **cur_res = &hyperv_mmio;
@@ -2359,6 +2384,11 @@ static int vmbus_device_add(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	if (!__is_defined(HYPERVISOR_CALLBACK_VECTOR))
+		ret = vmbus_set_irq(pdev);
+	if (ret)
+		return ret;
+
 	for_each_of_range(&parser, &range) {
 		struct resource *res;
 
-- 
2.43.0

[PATCH hyperv-next v8 09/11] Drivers: hv: vmbus: Introduce hv_get_vmbus_root_device()

[Roman Kisel]

The ARM64 PCI code for hyperv needs to know the VMBus root
device, and it is private.

Provide a function that returns it. Rename it from "hv_dev"
as "hv_dev" as a symbol is very overloaded. No functional
changes.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
---
 drivers/hv/vmbus_drv.c | 23 +++++++++++++++--------
 include/linux/hyperv.h |  2 ++
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index e8f2c3e92d1f..df18b4070b01 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -45,7 +45,8 @@ struct vmbus_dynid {
 	struct hv_vmbus_device_id id;
 };
 
-static struct device  *hv_dev;
+/* VMBus Root Device */
+static struct device  *vmbus_root_device;
 
 static int hyperv_cpuhp_online;
 
@@ -80,9 +81,15 @@ static struct resource *fb_mmio;
 static struct resource *hyperv_mmio;
 static DEFINE_MUTEX(hyperv_mmio_lock);
 
+struct device *hv_get_vmbus_root_device(void)
+{
+	return vmbus_root_device;
+}
+EXPORT_SYMBOL_GPL(hv_get_vmbus_root_device);
+
 static int vmbus_exists(void)
 {
-	if (hv_dev == NULL)
+	if (vmbus_root_device == NULL)
 		return -ENODEV;
 
 	return 0;
@@ -861,7 +868,7 @@ static int vmbus_dma_configure(struct device *child_device)
 	 * On x86/x64 coherence is assumed and these calls have no effect.
 	 */
 	hv_setup_dma_ops(child_device,
-		device_get_dma_attr(hv_dev) == DEV_DMA_COHERENT);
+		device_get_dma_attr(vmbus_root_device) == DEV_DMA_COHERENT);
 	return 0;
 }
 
@@ -1930,7 +1937,7 @@ int vmbus_device_register(struct hv_device *child_device_obj)
 		     &child_device_obj->channel->offermsg.offer.if_instance);
 
 	child_device_obj->device.bus = &hv_bus;
-	child_device_obj->device.parent = hv_dev;
+	child_device_obj->device.parent = vmbus_root_device;
 	child_device_obj->device.release = vmbus_device_release;
 
 	child_device_obj->device.dma_parms = &child_device_obj->dma_parms;
@@ -2292,7 +2299,7 @@ static int vmbus_acpi_add(struct platform_device *pdev)
 	struct acpi_device *ancestor;
 	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
 
-	hv_dev = &device->dev;
+	vmbus_root_device = &device->dev;
 
 	/*
 	 * Older versions of Hyper-V for ARM64 fail to include the _CCA
@@ -2378,7 +2385,7 @@ static int vmbus_device_add(struct platform_device *pdev)
 	struct device_node *np = pdev->dev.of_node;
 	int ret;
 
-	hv_dev = &pdev->dev;
+	vmbus_root_device = &pdev->dev;
 
 	ret = of_range_parser_init(&parser, np);
 	if (ret)
@@ -2696,7 +2703,7 @@ static int __init hv_acpi_init(void)
 	if (ret)
 		return ret;
 
-	if (!hv_dev) {
+	if (!vmbus_root_device) {
 		ret = -ENODEV;
 		goto cleanup;
 	}
@@ -2727,7 +2734,7 @@ static int __init hv_acpi_init(void)
 
 cleanup:
 	platform_driver_unregister(&vmbus_platform_driver);
-	hv_dev = NULL;
+	vmbus_root_device = NULL;
 	return ret;
 }
 
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 675959fb97ba..1f310fbbc4f9 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1277,6 +1277,8 @@ static inline void *hv_get_drvdata(struct hv_device *dev)
 	return dev_get_drvdata(&dev->device);
 }
 
+struct device *hv_get_vmbus_root_device(void);
+
 struct hv_ring_buffer_debug_info {
 	u32 current_interrupt_mask;
 	u32 current_read_index;
-- 
2.43.0

[PATCH hyperv-next v8 10/11] ACPI: irq: Introduce acpi_get_gsi_dispatcher()

[Roman Kisel]

Using acpi_irq_create_hierarchy() in the cases where the code
also handles OF leads to code duplication as the ACPI subsystem
doesn't provide means to compute the IRQ domain parent whereas
the OF does.

Introduce acpi_get_gsi_dispatcher() so that the drivers relying
on both ACPI and OF may use irq_domain_create_hierarchy() in the
common code paths.

No functional changes.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/irq.c   | 16 ++++++++++++++--
 include/linux/acpi.h |  5 ++++-
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/irq.c b/drivers/acpi/irq.c
index 1687483ff319..76a856c32c4d 100644
--- a/drivers/acpi/irq.c
+++ b/drivers/acpi/irq.c
@@ -12,7 +12,7 @@
 
 enum acpi_irq_model_id acpi_irq_model;
 
-static struct fwnode_handle *(*acpi_get_gsi_domain_id)(u32 gsi);
+static acpi_gsi_domain_disp_fn acpi_get_gsi_domain_id;
 static u32 (*acpi_gsi_to_irq_fallback)(u32 gsi);
 
 /**
@@ -307,12 +307,24 @@ EXPORT_SYMBOL_GPL(acpi_irq_get);
  *	for a given GSI
  */
 void __init acpi_set_irq_model(enum acpi_irq_model_id model,
-			       struct fwnode_handle *(*fn)(u32))
+			       acpi_gsi_domain_disp_fn fn)
 {
 	acpi_irq_model = model;
 	acpi_get_gsi_domain_id = fn;
 }
 
+/*
+ * acpi_get_gsi_dispatcher() - Get the GSI dispatcher function
+ *
+ * Return the dispatcher function that computes the domain fwnode for
+ * a given GSI.
+ */
+acpi_gsi_domain_disp_fn acpi_get_gsi_dispatcher(void)
+{
+	return acpi_get_gsi_domain_id;
+}
+EXPORT_SYMBOL_GPL(acpi_get_gsi_dispatcher);
+
 /**
  * acpi_set_gsi_to_irq_fallback - Register a GSI transfer
  * callback to fallback to arch specified implementation.
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 4e495b29c640..1917044dea72 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -336,8 +336,11 @@ int acpi_register_gsi (struct device *dev, u32 gsi, int triggering, int polarity
 int acpi_gsi_to_irq (u32 gsi, unsigned int *irq);
 int acpi_isa_irq_to_gsi (unsigned isa_irq, u32 *gsi);
 
+typedef struct fwnode_handle *(*acpi_gsi_domain_disp_fn)(u32);
+
 void acpi_set_irq_model(enum acpi_irq_model_id model,
-			struct fwnode_handle *(*)(u32));
+			acpi_gsi_domain_disp_fn fn);
+acpi_gsi_domain_disp_fn acpi_get_gsi_dispatcher(void);
 void acpi_set_gsi_to_irq_fallback(u32 (*)(u32));
 
 struct irq_domain *acpi_irq_create_hierarchy(unsigned int flags,
-- 
2.43.0

[PATCH hyperv-next v8 11/11] PCI: hv: Get vPCI MSI IRQ domain from DeviceTree

[Roman Kisel]

The hyperv-pci driver uses ACPI for MSI IRQ domain configuration on
arm64. It won't be able to do that in the VTL mode where only DeviceTree
can be used.

Update the hyperv-pci driver to get vPCI MSI IRQ domain in the DeviceTree
case, too.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/pci/controller/pci-hyperv.c | 72 ++++++++++++++++++++++++++---
 1 file changed, 66 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 6084b38bdda1..2d7de07bbf38 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -50,6 +50,7 @@
 #include <linux/irqdomain.h>
 #include <linux/acpi.h>
 #include <linux/sizes.h>
+#include <linux/of_irq.h>
 #include <asm/mshyperv.h>
 
 /*
@@ -817,9 +818,17 @@ static int hv_pci_vec_irq_gic_domain_alloc(struct irq_domain *domain,
 	int ret;
 
 	fwspec.fwnode = domain->parent->fwnode;
-	fwspec.param_count = 2;
-	fwspec.param[0] = hwirq;
-	fwspec.param[1] = IRQ_TYPE_EDGE_RISING;
+	if (is_of_node(fwspec.fwnode)) {
+		/* SPI lines for OF translations start at offset 32 */
+		fwspec.param_count = 3;
+		fwspec.param[0] = 0;
+		fwspec.param[1] = hwirq - 32;
+		fwspec.param[2] = IRQ_TYPE_EDGE_RISING;
+	} else {
+		fwspec.param_count = 2;
+		fwspec.param[0] = hwirq;
+		fwspec.param[1] = IRQ_TYPE_EDGE_RISING;
+	}
 
 	ret = irq_domain_alloc_irqs_parent(domain, virq, 1, &fwspec);
 	if (ret)
@@ -887,10 +896,46 @@ static const struct irq_domain_ops hv_pci_domain_ops = {
 	.activate = hv_pci_vec_irq_domain_activate,
 };
 
+#ifdef CONFIG_OF
+
+static struct irq_domain *hv_pci_of_irq_domain_parent(void)
+{
+	struct device_node *parent;
+	struct irq_domain *domain;
+
+	parent = of_irq_find_parent(hv_get_vmbus_root_device()->of_node);
+	if (!parent)
+		return NULL;
+	domain = irq_find_host(parent);
+	of_node_put(parent);
+
+	return domain;
+}
+
+#endif
+
+#ifdef CONFIG_ACPI
+
+static struct irq_domain *hv_pci_acpi_irq_domain_parent(void)
+{
+	acpi_gsi_domain_disp_fn gsi_domain_disp_fn;
+
+	if (acpi_irq_model != ACPI_IRQ_MODEL_GIC)
+		return NULL;
+	gsi_domain_disp_fn = acpi_get_gsi_dispatcher();
+	if (!gsi_domain_disp_fn)
+		return NULL;
+	return irq_find_matching_fwnode(gsi_domain_disp_fn(0),
+				     DOMAIN_BUS_ANY);
+}
+
+#endif
+
 static int hv_pci_irqchip_init(void)
 {
 	static struct hv_pci_chip_data *chip_data;
 	struct fwnode_handle *fn = NULL;
+	struct irq_domain *irq_domain_parent = NULL;
 	int ret = -ENOMEM;
 
 	chip_data = kzalloc(sizeof(*chip_data), GFP_KERNEL);
@@ -907,9 +952,24 @@ static int hv_pci_irqchip_init(void)
 	 * way to ensure that all the corresponding devices are also gone and
 	 * no interrupts will be generated.
 	 */
-	hv_msi_gic_irq_domain = acpi_irq_create_hierarchy(0, HV_PCI_MSI_SPI_NR,
-							  fn, &hv_pci_domain_ops,
-							  chip_data);
+#ifdef CONFIG_ACPI
+	if (!acpi_disabled)
+		irq_domain_parent = hv_pci_acpi_irq_domain_parent();
+#endif
+#ifdef CONFIG_OF
+	if (!irq_domain_parent)
+		irq_domain_parent = hv_pci_of_irq_domain_parent();
+#endif
+	if (!irq_domain_parent) {
+		WARN_ONCE(1, "Invalid firmware configuration for VMBus interrupts\n");
+		ret = -EINVAL;
+		goto free_chip;
+	}
+
+	hv_msi_gic_irq_domain = irq_domain_create_hierarchy(irq_domain_parent, 0,
+		HV_PCI_MSI_SPI_NR,
+		fn, &hv_pci_domain_ops,
+		chip_data);
 
 	if (!hv_msi_gic_irq_domain) {
 		pr_err("Failed to create Hyper-V arm64 vPCI MSI IRQ domain\n");
-- 
2.43.0

RE: [PATCH hyperv-next v8 01/11] arm64: kvm, smccc: Introduce and use API for getting hypervisor UUID

[Michael Kelley]

From: Roman Kisel <romank@linux.microsoft.com> Sent: Monday, April 14, 2025 3:47 PM
> 
> The KVM/arm64 uses SMCCC to detect hypervisor presence. That code is
> private, and it follows the SMCCC specification. Other existing and
> emerging hypervisor guest implementations can and should use that
> standard approach as well.
> 
> Factor out a common infrastructure that the guests can use, update KVM
> to employ the new API. The central notion of the SMCCC method is the
> UUID of the hypervisor, and the new API follows that.
> 
> No functional changes. Validated with a KVM/arm64 guest.
> 
> Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
> ---
>  arch/arm64/kvm/hypercalls.c        | 10 +++--
>  drivers/firmware/smccc/kvm_guest.c | 10 +----
>  drivers/firmware/smccc/smccc.c     | 17 ++++++++
>  include/linux/arm-smccc.h          | 64 ++++++++++++++++++++++++++++--
>  4 files changed, 85 insertions(+), 16 deletions(-)
> 

Reviewed-by: Michael Kelley <mhklinux@outlook.com>

RE: [PATCH hyperv-next v8 02/11] arm64: hyperv: Use SMCCC to detect hypervisor presence

[Michael Kelley]

From: Roman Kisel <romank@linux.microsoft.com> Sent: Monday, April 14, 2025 3:47 PM
> 
> The arm64 Hyper-V startup path relies on ACPI to detect
> running under a Hyper-V compatible hypervisor. That
> doesn't work on non-ACPI systems.
> 
> Hoist the ACPI detection logic into a separate function. Then
> use the vendor-specific hypervisor service call (implemented
> recently in Hyper-V) via SMCCC in the non-ACPI case.
> 
> Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
> ---
>  arch/arm64/hyperv/mshyperv.c | 50 ++++++++++++++++++++++++++++++++----
>  1 file changed, 45 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
> index 4e27cc29c79e..21458b6338aa 100644
> --- a/arch/arm64/hyperv/mshyperv.c
> +++ b/arch/arm64/hyperv/mshyperv.c
> @@ -28,6 +28,48 @@ int hv_get_hypervisor_version(union
> hv_hypervisor_version_info *info)
>  }
>  EXPORT_SYMBOL_GPL(hv_get_hypervisor_version);
> 
> +#ifdef CONFIG_ACPI
> +
> +static bool __init hyperv_detect_via_acpi(void)
> +{
> +	if (acpi_disabled)
> +		return false;
> +	/*
> +	 * Hypervisor ID is only available in ACPI v6+, and the
> +	 * structure layout was extended in v6 to accommodate that
> +	 * new field.
> +	 *
> +	 * At the very minimum, this check makes sure not to read
> +	 * past the FADT structure.
> +	 *
> +	 * It is also needed to catch running in some unknown
> +	 * non-Hyper-V environment that has ACPI 5.x or less.
> +	 * In such a case, it can't be Hyper-V.
> +	 */
> +	if (acpi_gbl_FADT.header.revision < 6)
> +		return false;
> +	return strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8) == 0;
> +}
> +
> +#else
> +
> +static bool __init hyperv_detect_via_acpi(void)
> +{
> +	return false;
> +}
> +
> +#endif
> +
> +static bool __init hyperv_detect_via_smccc(void)
> +{
> +	uuid_t hyperv_uuid = UUID_INIT(
> +		0x58ba324d, 0x6447, 0x24cd,
> +		0x75, 0x6c, 0xef, 0x8e,
> +		0x24, 0x70, 0x59, 0x16);

I had previously given my Reviewed-by: on v5 of this patch. But
looking at it again, it would be nice if this UUID were defined in
include/linux/arm-smccc.h alongside the definition of
ARM_SMCCC_VENDOR_HYP_UID_KVM. The UUID values are
are independent of each other, but it's a bit asymmetric to have
the KVM UUID defined centrally while the Hyper-V UUID is
buried in Hyper-V specific code. But I'm OK with the current code
if there's nothing else to respin for.

> +
> +	return arm_smccc_hypervisor_has_uuid(&hyperv_uuid);
> +}
> +
>  static int __init hyperv_init(void)
>  {
>  	struct hv_get_vp_registers_output	result;
> @@ -36,13 +78,11 @@ static int __init hyperv_init(void)
> 
>  	/*
>  	 * Allow for a kernel built with CONFIG_HYPERV to be running in
> -	 * a non-Hyper-V environment, including on DT instead of ACPI.
> +	 * a non-Hyper-V environment.
> +	 *
>  	 * In such cases, do nothing and return success.
>  	 */
> -	if (acpi_disabled)
> -		return 0;
> -
> -	if (strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8))
> +	if (!hyperv_detect_via_acpi() && !hyperv_detect_via_smccc())
>  		return 0;
> 
>  	/* Setup the guest ID */
> --
> 2.43.0
> 

My UUID comment notwithstanding,

Reviewed-by: Michael Kelley <mhklinux@outlook.com>

RE: [PATCH hyperv-next v8 03/11] Drivers: hv: Enable VTL mode for arm64

[Michael Kelley]

From: Roman Kisel <romank@linux.microsoft.com> Sent: Monday, April 14, 2025 3:47 PM
> 
> Kconfig dependencies for arm64 guests on Hyper-V require that be
> ACPI enabled, and limit VTL mode to x86/x64. To enable VTL mode
> on arm64 as well, update the dependencies. Since VTL mode requires
> DeviceTree instead of ACPI, don’t require arm64 guests on Hyper-V
> to have ACPI unconditionally.
> 
> Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
> ---
>  drivers/hv/Kconfig | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
> index 6c1416167bd2..eefa0b559b73 100644
> --- a/drivers/hv/Kconfig
> +++ b/drivers/hv/Kconfig
> @@ -5,7 +5,7 @@ menu "Microsoft Hyper-V guest support"
>  config HYPERV
>  	tristate "Microsoft Hyper-V client drivers"
>  	depends on (X86 && X86_LOCAL_APIC && HYPERVISOR_GUEST) \
> -		|| (ACPI && ARM64 && !CPU_BIG_ENDIAN)
> +		|| (ARM64 && !CPU_BIG_ENDIAN)
>  	select PARAVIRT
>  	select X86_HV_CALLBACK_VECTOR if X86
>  	select OF_EARLY_FLATTREE if OF
> @@ -15,7 +15,7 @@ config HYPERV
> 
>  config HYPERV_VTL_MODE
>  	bool "Enable Linux to boot in VTL context"
> -	depends on X86_64 && HYPERV
> +	depends on (X86_64 || ARM64) && HYPERV
>  	depends on SMP
>  	default n
>  	help
> @@ -31,7 +31,7 @@ config HYPERV_VTL_MODE
> 
>  	  Select this option to build a Linux kernel to run at a VTL other than
>  	  the normal VTL0, which currently is only VTL2.  This option
> -	  initializes the x86 platform for VTL2, and adds the ability to boot
> +	  initializes the kernel to run in VTL2, and adds the ability to boot
>  	  secondary CPUs directly into 64-bit context as required for VTLs other
>  	  than 0.  A kernel built with this option must run at VTL2, and will
>  	  not run as a normal guest.
> --
> 2.43.0
> 

Reviewed-by: Michael Kelley <mhklinux@outlook.com>

RE: [PATCH hyperv-next v8 06/11] arm64, x86: hyperv: Report the VTL the system boots in

[Michael Kelley]

From: Roman Kisel <romank@linux.microsoft.com> Sent: Monday, April 14, 2025 3:47 PM
> 
> The hyperv guest code might run in various Virtual Trust Levels.
> 
> Report the level when the kernel boots in the non-default (0)
> one.
> 
> Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
> ---
>  arch/arm64/hyperv/mshyperv.c | 2 ++
>  arch/x86/hyperv/hv_vtl.c     | 7 ++++++-
>  2 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
> index 43f422a7ef34..4fdc26ade1d7 100644
> --- a/arch/arm64/hyperv/mshyperv.c
> +++ b/arch/arm64/hyperv/mshyperv.c
> @@ -118,6 +118,8 @@ static int __init hyperv_init(void)
>  	if (ms_hyperv.priv_high & HV_ACCESS_PARTITION_ID)
>  		hv_get_partition_id();
>  	ms_hyperv.vtl = get_vtl();
> +	if (ms_hyperv.vtl > 0) /* non default VTL */
> +		pr_info("Linux runs in Hyper-V Virtual Trust Level %d\n", ms_hyperv.vtl);
> 
>  	ms_hyperv_late_init();
> 
> diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c
> index 582fe820e29c..038c896fdd60 100644
> --- a/arch/x86/hyperv/hv_vtl.c
> +++ b/arch/x86/hyperv/hv_vtl.c
> @@ -55,7 +55,12 @@ static void  __noreturn hv_vtl_restart(char __maybe_unused *cmd)
> 
>  void __init hv_vtl_init_platform(void)
>  {
> -	pr_info("Linux runs in Hyper-V Virtual Trust Level\n");
> +	/*
> +	 * This function is a no-op if the VTL mode is not enabled.
> +	 * If it is, this function runs if and only the kernel boots in
> +	 * VTL2 which the x86 hv initialization path makes sure of.
> +	 */
> +	pr_info("Linux runs in Hyper-V Virtual Trust Level %d\n", ms_hyperv.vtl);
> 
>  	x86_platform.realmode_reserve = x86_init_noop;
>  	x86_platform.realmode_init = x86_init_noop;
> --
> 2.43.0
> 

Reviewed-by: Michael Kelley <mhklinux@outlook.com>

RE: [PATCH hyperv-next v8 11/11] PCI: hv: Get vPCI MSI IRQ domain from DeviceTree

[Michael Kelley]

From: Roman Kisel <romank@linux.microsoft.com> Sent: Monday, April 14, 2025 3:47 PM
> 
> The hyperv-pci driver uses ACPI for MSI IRQ domain configuration on
> arm64. It won't be able to do that in the VTL mode where only DeviceTree
> can be used.
> 
> Update the hyperv-pci driver to get vPCI MSI IRQ domain in the DeviceTree
> case, too.
> 
> Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
> Acked-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
>  drivers/pci/controller/pci-hyperv.c | 72 ++++++++++++++++++++++++++---
>  1 file changed, 66 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index 6084b38bdda1..2d7de07bbf38 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -50,6 +50,7 @@
>  #include <linux/irqdomain.h>
>  #include <linux/acpi.h>
>  #include <linux/sizes.h>
> +#include <linux/of_irq.h>
>  #include <asm/mshyperv.h>
> 
>  /*
> @@ -817,9 +818,17 @@ static int hv_pci_vec_irq_gic_domain_alloc(struct irq_domain *domain,
>  	int ret;
> 
>  	fwspec.fwnode = domain->parent->fwnode;
> -	fwspec.param_count = 2;
> -	fwspec.param[0] = hwirq;
> -	fwspec.param[1] = IRQ_TYPE_EDGE_RISING;
> +	if (is_of_node(fwspec.fwnode)) {
> +		/* SPI lines for OF translations start at offset 32 */
> +		fwspec.param_count = 3;
> +		fwspec.param[0] = 0;
> +		fwspec.param[1] = hwirq - 32;
> +		fwspec.param[2] = IRQ_TYPE_EDGE_RISING;
> +	} else {
> +		fwspec.param_count = 2;
> +		fwspec.param[0] = hwirq;
> +		fwspec.param[1] = IRQ_TYPE_EDGE_RISING;
> +	}
> 
>  	ret = irq_domain_alloc_irqs_parent(domain, virq, 1, &fwspec);
>  	if (ret)
> @@ -887,10 +896,46 @@ static const struct irq_domain_ops hv_pci_domain_ops = {
>  	.activate = hv_pci_vec_irq_domain_activate,
>  };
> 
> +#ifdef CONFIG_OF
> +
> +static struct irq_domain *hv_pci_of_irq_domain_parent(void)
> +{
> +	struct device_node *parent;
> +	struct irq_domain *domain;
> +
> +	parent = of_irq_find_parent(hv_get_vmbus_root_device()->of_node);
> +	if (!parent)
> +		return NULL;
> +	domain = irq_find_host(parent);
> +	of_node_put(parent);
> +
> +	return domain;
> +}
> +
> +#endif
> +
> +#ifdef CONFIG_ACPI
> +
> +static struct irq_domain *hv_pci_acpi_irq_domain_parent(void)
> +{
> +	acpi_gsi_domain_disp_fn gsi_domain_disp_fn;
> +
> +	if (acpi_irq_model != ACPI_IRQ_MODEL_GIC)
> +		return NULL;

This causes a build error on arm64 if pci-hyperv.c is built as a
module because acpi_irq_model is not exported.

Michael

> +	gsi_domain_disp_fn = acpi_get_gsi_dispatcher();
> +	if (!gsi_domain_disp_fn)
> +		return NULL;
> +	return irq_find_matching_fwnode(gsi_domain_disp_fn(0),
> +				     DOMAIN_BUS_ANY);
> +}
> +
> +#endif
> +
>  static int hv_pci_irqchip_init(void)
>  {
>  	static struct hv_pci_chip_data *chip_data;
>  	struct fwnode_handle *fn = NULL;
> +	struct irq_domain *irq_domain_parent = NULL;
>  	int ret = -ENOMEM;
> 
>  	chip_data = kzalloc(sizeof(*chip_data), GFP_KERNEL);
> @@ -907,9 +952,24 @@ static int hv_pci_irqchip_init(void)
>  	 * way to ensure that all the corresponding devices are also gone and
>  	 * no interrupts will be generated.
>  	 */
> -	hv_msi_gic_irq_domain = acpi_irq_create_hierarchy(0, HV_PCI_MSI_SPI_NR,
> -							  fn, &hv_pci_domain_ops,
> -							  chip_data);
> +#ifdef CONFIG_ACPI
> +	if (!acpi_disabled)
> +		irq_domain_parent = hv_pci_acpi_irq_domain_parent();
> +#endif
> +#ifdef CONFIG_OF
> +	if (!irq_domain_parent)
> +		irq_domain_parent = hv_pci_of_irq_domain_parent();
> +#endif
> +	if (!irq_domain_parent) {
> +		WARN_ONCE(1, "Invalid firmware configuration for VMBus interrupts\n");
> +		ret = -EINVAL;
> +		goto free_chip;
> +	}
> +
> +	hv_msi_gic_irq_domain = irq_domain_create_hierarchy(irq_domain_parent, 0,
> +		HV_PCI_MSI_SPI_NR,
> +		fn, &hv_pci_domain_ops,
> +		chip_data);
> 
>  	if (!hv_msi_gic_irq_domain) {
>  		pr_err("Failed to create Hyper-V arm64 vPCI MSI IRQ domain\n");
> --
> 2.43.0
> 

Re: [PATCH hyperv-next v8 02/11] arm64: hyperv: Use SMCCC to detect hypervisor presence

[Roman Kisel]

On 4/17/2025 8:27 AM, Michael Kelley wrote:
> From: Roman Kisel <romank@linux.microsoft.com> Sent: Monday, April 14, 2025 3:47 PM
[...]
> I had previously given my Reviewed-by: on v5 of this patch. But
> looking at it again, it would be nice if this UUID were defined in
> include/linux/arm-smccc.h alongside the definition of
> ARM_SMCCC_VENDOR_HYP_UID_KVM. The UUID values are
> are independent of each other, but it's a bit asymmetric to have
> the KVM UUID defined centrally while the Hyper-V UUID is
> buried in Hyper-V specific code. But I'm OK with the current code
> if there's nothing else to respin for.
> 

As I saw that, KVM is special in the kernel as the kernel provides
both the host side code and the kernel side code so the UUID has
to be shared in the header file.

In the Hyper-V case, we have only the guest side code so it seemed
more economical to have that tucked into the function rather than
adding to the arch-wide header and including the header.


>> +
>> +	return arm_smccc_hypervisor_has_uuid(&hyperv_uuid);
>> +}
>> +
>>   static int __init hyperv_init(void)
>>   {
>>   	struct hv_get_vp_registers_output	result;
>> @@ -36,13 +78,11 @@ static int __init hyperv_init(void)
>>
>>   	/*
>>   	 * Allow for a kernel built with CONFIG_HYPERV to be running in
>> -	 * a non-Hyper-V environment, including on DT instead of ACPI.
>> +	 * a non-Hyper-V environment.
>> +	 *
>>   	 * In such cases, do nothing and return success.
>>   	 */
>> -	if (acpi_disabled)
>> -		return 0;
>> -
>> -	if (strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8))
>> +	if (!hyperv_detect_via_acpi() && !hyperv_detect_via_smccc())
>>   		return 0;
>>
>>   	/* Setup the guest ID */
>> --
>> 2.43.0
>>
> 
> My UUID comment notwithstanding,
> 
> Reviewed-by: Michael Kelley <mhklinux@outlook.com>
> 
> 

-- 
Thank you,
Roman

Re: [PATCH hyperv-next v8 11/11] PCI: hv: Get vPCI MSI IRQ domain from DeviceTree

[Roman Kisel]

On 4/17/2025 8:28 AM, Michael Kelley wrote:
> From: Roman Kisel <romank@linux.microsoft.com> Sent: Monday, April 14, 2025 3:47 PM
[...]

>> +	if (acpi_irq_model != ACPI_IRQ_MODEL_GIC)
>> +		return NULL;
> 
> This causes a build error on arm64 if pci-hyperv.c is built as a
> module because acpi_irq_model is not exported.

Will fix that! Appreciate your reviews very much!

> 
> Michael
> 
>> +	gsi_domain_disp_fn = acpi_get_gsi_dispatcher();
>> +	if (!gsi_domain_disp_fn)
>> +		return NULL;
>> +	return irq_find_matching_fwnode(gsi_domain_disp_fn(0),
>> +				     DOMAIN_BUS_ANY);
>> +}
>> +
>> +#endif
>> +
>>   static int hv_pci_irqchip_init(void)
>>   {
>>   	static struct hv_pci_chip_data *chip_data;
>>   	struct fwnode_handle *fn = NULL;
>> +	struct irq_domain *irq_domain_parent = NULL;
>>   	int ret = -ENOMEM;
>>
>>   	chip_data = kzalloc(sizeof(*chip_data), GFP_KERNEL);
>> @@ -907,9 +952,24 @@ static int hv_pci_irqchip_init(void)
>>   	 * way to ensure that all the corresponding devices are also gone and
>>   	 * no interrupts will be generated.
>>   	 */
>> -	hv_msi_gic_irq_domain = acpi_irq_create_hierarchy(0, HV_PCI_MSI_SPI_NR,
>> -							  fn, &hv_pci_domain_ops,
>> -							  chip_data);
>> +#ifdef CONFIG_ACPI
>> +	if (!acpi_disabled)
>> +		irq_domain_parent = hv_pci_acpi_irq_domain_parent();
>> +#endif
>> +#ifdef CONFIG_OF
>> +	if (!irq_domain_parent)
>> +		irq_domain_parent = hv_pci_of_irq_domain_parent();
>> +#endif
>> +	if (!irq_domain_parent) {
>> +		WARN_ONCE(1, "Invalid firmware configuration for VMBus interrupts\n");
>> +		ret = -EINVAL;
>> +		goto free_chip;
>> +	}
>> +
>> +	hv_msi_gic_irq_domain = irq_domain_create_hierarchy(irq_domain_parent, 0,
>> +		HV_PCI_MSI_SPI_NR,
>> +		fn, &hv_pci_domain_ops,
>> +		chip_data);
>>
>>   	if (!hv_msi_gic_irq_domain) {
>>   		pr_err("Failed to create Hyper-V arm64 vPCI MSI IRQ domain\n");
>> --
>> 2.43.0
>>
> 

-- 
Thank you,
Roman