x86/hyperv: Set Virtual Trust Level in VMBus init message

SEV-SNP guests on Hyper-V can run at multiple Virtual Trust
Levels (VTL).  During boot, get the VTL at which we're running
using the GET_VP_REGISTERs hypercall, and save the value
for future use.  Then during VMBus initialization, set the VTL
with the saved value as required in the VMBus init message.

Reviewed-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Tianyu Lan <tiala@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Link: https://lore.kernel.org/r/20230818102919.1318039-3-ltykernel@gmail.com

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 6c04b52..318010e 100644 (file)
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -378,6 +378,36 @@ 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;
+       unsigned long flags;
+       u64 ret;
+
+       local_irq_save(flags);
+       input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+       output = (struct hv_get_vp_registers_output *)input;
+
+       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)) {
+               ret = output->as64.low & HV_X64_VTL_MASK;
+       } else {
+               pr_err("Failed to get VTL(%lld) and set VTL to zero by default.\n", ret);
+               ret = 0;
+       }
+
+       local_irq_restore(flags);
+       return ret;
+}
+
 /*
  * This function is to be invoked early in the boot sequence after the
  * hypervisor has been detected.
@@ -506,6 +536,10 @@ 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 */
+       if (hv_isolation_type_en_snp())
+               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 cea95dc..4bf0b31 100644 (file)
--- 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 5978e9d..02b54f8 100644 (file)
--- 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 580c766..efd0d2a 100644 (file)
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -54,6 +54,7 @@ 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 bfbc37c..1f2bfec 100644 (file)
--- 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;