[PATCH hyperv-next v6 04/11] Drivers: hv: Provide arch-neutral implementation of get_vtl()

Roman Kisel
2025-03-15T00:19:35Z

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 9804adb4cc56..dce4b34e293b 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -304,6 +304,37 @@ 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 b13b0cda4ac8..c5150a2b12d6 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -348,4 +348,10 @@ 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 58895883f636..98aa64e8844c 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