[PATCH v3 07/17] x86/hyperv: extract partition ID from Microsoft Hypervisor if necessary

[Wei Liu <wei.liu@kernel.org>]

We will need the partition ID for executing some hypercalls later.

Signed-off-by: Lillian Grassin-Drake <ligrassi@microsoft.com>
Co-Developed-by: Sunil Muthuswamy <sunilmut@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
---
v3:
1. Make hv_get_partition_id static.
2. Change code structure a bit.
---
 arch/x86/hyperv/hv_init.c         | 27 +++++++++++++++++++++++++++
 arch/x86/include/asm/mshyperv.h   |  2 ++
 include/asm-generic/hyperv-tlfs.h |  6 ++++++
 3 files changed, 35 insertions(+)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 6f4cb40e53fe..fc9941bd8653 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -26,6 +26,9 @@
 #include <linux/syscore_ops.h>
 #include <clocksource/hyperv_timer.h>
 
+u64 hv_current_partition_id = ~0ull;
+EXPORT_SYMBOL_GPL(hv_current_partition_id);
+
 void *hv_hypercall_pg;
 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
 
@@ -331,6 +334,25 @@ static struct syscore_ops hv_syscore_ops = {
 	.resume		= hv_resume,
 };
 
+static void __init hv_get_partition_id(void)
+{
+	struct hv_get_partition_id *output_page;
+	u16 status;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	output_page = *this_cpu_ptr(hyperv_pcpu_output_arg);
+	status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page) &
+		HV_HYPERCALL_RESULT_MASK;
+	if (status != HV_STATUS_SUCCESS) {
+		/* No point in proceeding if this failed */
+		pr_err("Failed to get partition ID: %d\n", status);
+		BUG();
+	}
+	hv_current_partition_id = output_page->partition_id;
+	local_irq_restore(flags);
+}
+
 /*
  * This function is to be invoked early in the boot sequence after the
  * hypervisor has been detected.
@@ -426,6 +448,11 @@ void __init hyperv_init(void)
 
 	register_syscore_ops(&hv_syscore_ops);
 
+	if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_ACCESS_PARTITION_ID)
+		hv_get_partition_id();
+
+	BUG_ON(hv_root_partition && hv_current_partition_id == ~0ull);
+
 	return;
 
 remove_cpuhp_state:
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 62d9390f1ddf..67f5d35a73d3 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -78,6 +78,8 @@ extern void *hv_hypercall_pg;
 extern void  __percpu  **hyperv_pcpu_input_arg;
 extern void  __percpu  **hyperv_pcpu_output_arg;
 
+extern u64 hv_current_partition_id;
+
 static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
 {
 	u64 input_address = input ? virt_to_phys(input) : 0;
diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
index e6903589a82a..87b1a79b19eb 100644
--- a/include/asm-generic/hyperv-tlfs.h
+++ b/include/asm-generic/hyperv-tlfs.h
@@ -141,6 +141,7 @@ struct ms_hyperv_tsc_page {
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX	0x0013
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX	0x0014
 #define HVCALL_SEND_IPI_EX			0x0015
+#define HVCALL_GET_PARTITION_ID			0x0046
 #define HVCALL_GET_VP_REGISTERS			0x0050
 #define HVCALL_SET_VP_REGISTERS			0x0051
 #define HVCALL_POST_MESSAGE			0x005c
@@ -407,6 +408,11 @@ struct hv_tlb_flush_ex {
 	u64 gva_list[];
 } __packed;
 
+/* HvGetPartitionId hypercall (output only) */
+struct hv_get_partition_id {
+	u64 partition_id;
+} __packed;
+
 /* HvRetargetDeviceInterrupt hypercall */
 union hv_msi_entry {
 	u64 as_uint64;
-- 
2.20.1