[PATCH 1/9] x86/hyperv: Add hv_isolation_type_tdx() to detect TDX guests

Dexuan Cui
2023-08-11T22:19:53Z

No logic change to SNP/VBS guests.

hv_isolation_type_tdx() will be used to instruct a TDX guest on Hyper-V to
do some TDX-specific operations, e.g. for a fully enlightened TDX guest
(i.e. without the paravisor), hv_do_hypercall() should use
__tdx_hypercall() and such a guest on Hyper-V should handle the Hyper-V
Event/Message/Monitor pages specially.

Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
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 | 2 ++
drivers/hv/hv_common.c | 6 ++++++
include/asm-generic/mshyperv.h | 1 +
6 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index ee08a0cd6da38..d4aafe8b6b50d 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -524,3 +524,12 @@ bool hv_isolation_type_en_snp(void)
return static_branch_unlikely(&isolation_type_en_snp);
}

+DEFINE_STATIC_KEY_FALSE(isolation_type_tdx);
+/*
+ * hv_isolation_type_tdx - Check if the system runs in an Intel TDX based
+ * isolated VM.
+ */
+bool hv_isolation_type_tdx(void)
+{
+ return static_branch_unlikely(&isolation_type_tdx);
+}
diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index 4bf0b315b0ce9..2ff26f53cd624 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -169,7 +169,8 @@
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 0b0d1eb249d0a..83fc3a79f1557 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -27,6 +27,7 @@ union hv_ghcb;

DECLARE_STATIC_KEY_FALSE(isolation_type_snp);
DECLARE_STATIC_KEY_FALSE(isolation_type_en_snp);
+DECLARE_STATIC_KEY_FALSE(isolation_type_tdx);

typedef int (*hyperv_fill_flush_list_func)(
struct hv_guest_mapping_flush_list *flush,
@@ -59,6 +60,8 @@ 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);

+bool hv_isolation_type_tdx(void);
+
static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
{
u64 input_address = input ? virt_to_phys(input) : 0;
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index b7d73f3107c63..a50fd3650ea9b 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -418,6 +418,8 @@ static void __init ms_hyperv_init_platform(void)
static_branch_enable(&isolation_type_en_snp);
} else if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP) {
static_branch_enable(&isolation_type_snp);
+ } else if (hv_get_isolation_type() == HV_ISOLATION_TYPE_TDX) {
+ static_branch_enable(&isolation_type_tdx);
}
}

diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index 2d43ba2bc925d..da3307533f4d7 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -521,6 +521,12 @@ bool __weak hv_isolation_type_en_snp(void)
}
EXPORT_SYMBOL_GPL(hv_isolation_type_en_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))
{
}
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index efd0d2aedad39..c5e657c3cdf4c 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -66,6 +66,7 @@ extern u64 hv_do_hypercall(u64 control, void *inputaddr, void *outputaddr);
extern u64 hv_do_fast_hypercall8(u16 control, u64 input8);
extern bool hv_isolation_type_snp(void);
extern bool hv_isolation_type_en_snp(void);
+extern bool hv_isolation_type_tdx(void);

/* Helper functions that provide a consistent pattern for checking Hyper-V hypercall status. */
static inline int hv_result(u64 status)
--
2.25.1