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

Wei Liu
2020-11-24T17:09:00Z

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