linux-kernel - [PATCH hyperv-next v4 3/6] Drivers: hv: Provide arch-neutral implementation of get

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Message-ID: <20250212014321.1108840-4-romank@linux.microsoft.com>
Date: Tue, 11 Feb 2025 17:43:18 -0800
From: Roman Kisel <romank@...ux.microsoft.com>
To: arnd@...db.de,
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Cc: benhill@...rosoft.com,
	bperkins@...rosoft.com,
	sunilmut@...rosoft.com
Subject: [PATCH hyperv-next v4 3/6] Drivers: hv: Provide arch-neutral implementation of get_vtl()

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@...ux.microsoft.com>
---
 arch/x86/hyperv/hv_init.c      | 34 ----------------------------------
 drivers/hv/hv_common.c         | 32 ++++++++++++++++++++++++++++++++
 include/asm-generic/mshyperv.h |  6 ++++++
 include/hyperv/hvgdk_mini.h    |  2 +-
 4 files changed, 39 insertions(+), 35 deletions(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 173005e6a95d..383bca1a3ae2 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -411,40 +411,6 @@ static void __init hv_get_partition_id(void)
 	local_irq_restore(flags);
 }
 
-#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 af5d1dc451f6..70f754710170 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -283,6 +283,38 @@ static inline bool hv_output_page_exists(void)
 	return hv_root_partition || IS_ENABLED(CONFIG_HYPERV_VTL_MODE);
 }
 
+#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)
 {
 	int i;
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index a7bbe504e4f3..bb36856c3467 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -314,4 +314,10 @@ static inline enum hv_isolation_type hv_get_isolation_type(void)
 }
 #endif /* CONFIG_HYPERV */
 
+#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 155615175965..0f8443595732 100644
--- a/include/hyperv/hvgdk_mini.h
+++ b/include/hyperv/hvgdk_mini.h
@@ -1202,7 +1202,7 @@ 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