[RFC PATCH V5 03/15] x86/hyperv: Set Virtual Trust Level in VMBus init message

Tianyu Lan
2023-05-01T08:57:46Z

From: Tianyu Lan <tiala@microsoft.com>

sev-snp guest provides vtl(Virtual Trust Level) and
get it from hyperv hvcall via HVCALL_GET_VP_REGISTERS.
Set target vtl in the VMBus init message.

Signed-off-by: Tianyu Lan <tiala@microsoft.com>
---
Change since RFC v4:
* Use struct_size to calculate array size.
* Fix some coding style

Change since RFC v3:
* Use the standard helper functions to check hypercall result
* Fix coding style

Change since RFC v2:
* Rename get_current_vtl() to get_vtl()
* Fix some coding style issues
---
arch/x86/hyperv/hv_init.c | 36 ++++++++++++++++++++++++++++++
arch/x86/include/asm/hyperv-tlfs.h | 7 ++++++
drivers/hv/connection.c | 1 +
include/asm-generic/mshyperv.h | 1 +
include/linux/hyperv.h | 4 ++--
5 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 9f3e2d71d015..331b855314b7 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -384,6 +384,40 @@ static void __init hv_get_partition_id(void)
local_irq_restore(flags);
}

+static u8 __init get_vtl(void)
+{
+ u64 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_REGISTERS;
+ struct hv_get_vp_registers_input *input;
+ struct hv_get_vp_registers_output *output;
+ u64 vtl = 0;
+ u64 ret;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+ output = (struct hv_get_vp_registers_output *)input;
+ if (!input) {
+ local_irq_restore(flags);
+ goto done;
+ }
+
+ memset(input, 0, struct_size(input, element, 1));
+ input->header.partitionid = HV_PARTITION_ID_SELF;
+ input->header.vpindex = HV_VP_INDEX_SELF;
+ input->header.inputvtl = 0;
+ input->element[0].name0 = HV_X64_REGISTER_VSM_VP_STATUS;
+
+ ret = hv_do_hypercall(control, input, output);
+ if (hv_result_success(ret))
+ vtl = output->as64.low & HV_X64_VTL_MASK;
+ else
+ pr_err("Hyper-V: failed to get VTL! %lld", ret);
+ local_irq_restore(flags);
+
+done:
+ return vtl;
+}
+
/*
* This function is to be invoked early in the boot sequence after the
* hypervisor has been detected.
@@ -512,6 +546,8 @@ void __init hyperv_init(void)
/* Query the VMs extended capability once, so that it can be cached. */
hv_query_ext_cap(0);

+ /* Find the VTL */
+ ms_hyperv.vtl = get_vtl();
return;

clean_guest_os_id:
diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index cea95dcd27c2..4bf0b315b0ce 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -301,6 +301,13 @@ enum hv_isolation_type {
#define HV_X64_MSR_TIME_REF_COUNT HV_REGISTER_TIME_REF_COUNT
#define HV_X64_MSR_REFERENCE_TSC HV_REGISTER_REFERENCE_TSC

+/*
+ * Registers are only accessible via HVCALL_GET_VP_REGISTERS hvcall and
+ * there is not associated MSR address.
+ */
+#define HV_X64_REGISTER_VSM_VP_STATUS 0x000D0003
+#define HV_X64_VTL_MASK GENMASK(3, 0)
+
/* Hyper-V memory host visibility */
enum hv_mem_host_visibility {
VMBUS_PAGE_NOT_VISIBLE = 0,
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 5978e9dbc286..02b54f85dc60 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -98,6 +98,7 @@ int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
*/
if (version >= VERSION_WIN10_V5) {
msg->msg_sint = VMBUS_MESSAGE_SINT;
+ msg->msg_vtl = ms_hyperv.vtl;
vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
} else {
msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index 402a8c1c202d..3052130ba4ef 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -48,6 +48,7 @@ struct ms_hyperv_info {
};
};
u64 shared_gpa_boundary;
+ u8 vtl;
};
extern struct ms_hyperv_info ms_hyperv;
extern bool hv_nested;
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index bfbc37ce223b..1f2bfec4abde 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -665,8 +665,8 @@ struct vmbus_channel_initiate_contact {
u64 interrupt_page;
struct {
u8 msg_sint;
- u8 padding1[3];
- u32 padding2;
+ u8 msg_vtl;
+ u8 reserved[6];
};
};
u64 monitor_page1;
--
2.25.1