[PATCH v2 3/6] x86/hyperv: Add hv_isolation_type_tdx() to detect TDX guests

From: Dexuan Cui
Date: Tue Dec 06 2022 - 19:35:54 EST


No logic change to SNP/VBS guests.

hv_isolation_type_tdx() wil be used to instruct a TDX guest on Hyper-V to
do some TDX-specific operations, e.g. hv_do_hypercall() should use
__tdx_hypercall(), and a TDX guest on Hyper-V should handle the Hyper-V
Event/Message/Monitor pages specially.

Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>

---

Changes in v2:
Added "#ifdef CONFIG_INTEL_TDX_GUEST and #endif" for
hv_isolation_type_tdx() in arch/x86/hyperv/ivm.c.

Simplified the changes in ms_hyperv_init_platform().

arch/x86/hyperv/ivm.c | 9 +++++++++
arch/x86/include/asm/hyperv-tlfs.h | 3 ++-
arch/x86/include/asm/mshyperv.h | 3 +++
arch/x86/kernel/cpu/mshyperv.c | 7 ++++++-
drivers/hv/hv_common.c | 6 ++++++
5 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index 1dbcbd9da74d..13ccb52eecd7 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -269,6 +269,15 @@ bool hv_isolation_type_snp(void)
return static_branch_unlikely(&isolation_type_snp);
}

+#ifdef CONFIG_INTEL_TDX_GUEST
+DEFINE_STATIC_KEY_FALSE(isolation_type_tdx);
+
+bool hv_isolation_type_tdx(void)
+{
+ return static_branch_unlikely(&isolation_type_tdx);
+}
+#endif
+
/*
* hv_mark_gpa_visibility - Set pages visible to host via hvcall.
*
diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index 6d9368ea3701..6c0a04d078f5 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -161,7 +161,8 @@
enum hv_isolation_type {
HV_ISOLATION_TYPE_NONE = 0,
HV_ISOLATION_TYPE_VBS = 1,
- HV_ISOLATION_TYPE_SNP = 2
+ HV_ISOLATION_TYPE_SNP = 2,
+ HV_ISOLATION_TYPE_TDX = 3
};

/* Hyper-V specific model specific registers (MSRs) */
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 61f0c206bff0..8a2cafec4675 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -14,6 +14,7 @@
union hv_ghcb;

DECLARE_STATIC_KEY_FALSE(isolation_type_snp);
+DECLARE_STATIC_KEY_FALSE(isolation_type_tdx);

typedef int (*hyperv_fill_flush_list_func)(
struct hv_guest_mapping_flush_list *flush,
@@ -32,6 +33,8 @@ extern u64 hv_current_partition_id;

extern union hv_ghcb * __percpu *hv_ghcb_pg;

+extern bool hv_isolation_type_tdx(void);
+
int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages);
int hv_call_add_logical_proc(int node, u32 lp_index, u32 acpi_id);
int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u32 flags);
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 46668e255421..941372449ff2 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -339,9 +339,14 @@ static void __init ms_hyperv_init_platform(void)
}
/* Isolation VMs are unenlightened SEV-based VMs, thus this check: */
if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) {
- if (hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE)
+ if (hv_get_isolation_type() == HV_ISOLATION_TYPE_VBS ||
+ hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP)
cc_set_vendor(CC_VENDOR_HYPERV);
}
+
+ if (IS_ENABLED(CONFIG_INTEL_TDX_GUEST) &&
+ hv_get_isolation_type() == HV_ISOLATION_TYPE_TDX)
+ static_branch_enable(&isolation_type_tdx);
}

if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) {
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index ae68298c0dca..a9a03ab04b97 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -268,6 +268,12 @@ bool __weak hv_isolation_type_snp(void)
}
EXPORT_SYMBOL_GPL(hv_isolation_type_snp);

+bool __weak hv_isolation_type_tdx(void)
+{
+ return false;
+}
+EXPORT_SYMBOL_GPL(hv_isolation_type_tdx);
+
void __weak hv_setup_vmbus_handler(void (*handler)(void))
{
}
--
2.25.1