[PATCH 5/6] x86/hyperv: Support hypercalls for TDX guests

[Dexuan Cui <decui@microsoft.com>]

A TDX guest uses the GHCI call rather than hv_hypercall_pg.

In hv_do_hypercall(), Hyper-V requires that the input/output addresses
must have the vTOM bit set. With current Hyper-V, the bit for TDX is
bit 47, which is saved into ms_hyperv.shared_gpa_boundary() in
ms_hyperv_init_platform().

arch/x86/include/asm/mshyperv.h: hv_do_hypercall() needs
"struct ms_hyperv_info", which is defined in
include/asm-generic/mshyperv.h, which can't be included in
arch/x86/include/asm/mshyperv.h because include/asm-generic/mshyperv.h
has vmbus_signal_eom() -> hv_set_register(), which is defined in
arch/x86/include/asm/mshyperv.h.

Break this circular dependency by introducing a new header file
for "struct ms_hyperv_info".

Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
 MAINTAINERS                          |  1 +
 arch/x86/hyperv/hv_init.c            |  8 ++++++++
 arch/x86/include/asm/mshyperv.h      | 24 ++++++++++++++++++++++-
 arch/x86/kernel/cpu/mshyperv.c       |  2 ++
 include/asm-generic/ms_hyperv_info.h | 29 ++++++++++++++++++++++++++++
 include/asm-generic/mshyperv.h       | 24 +----------------------
 6 files changed, 64 insertions(+), 24 deletions(-)
 create mode 100644 include/asm-generic/ms_hyperv_info.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 256f03904987..455ecaf188fe 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9537,6 +9537,7 @@ F:	drivers/scsi/storvsc_drv.c
 F:	drivers/uio/uio_hv_generic.c
 F:	drivers/video/fbdev/hyperv_fb.c
 F:	include/asm-generic/hyperv-tlfs.h
+F:	include/asm-generic/ms_hyperv_info.h
 F:	include/asm-generic/mshyperv.h
 F:	include/clocksource/hyperv_timer.h
 F:	include/linux/hyperv.h
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 89954490af93..05682c4e327f 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -432,6 +432,10 @@ void __init hyperv_init(void)
 	/* Hyper-V requires to write guest os id via ghcb in SNP IVM. */
 	hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, guest_id);
 
+	/* A TDX guest uses the GHCI call rather than hv_hypercall_pg. */
+	if (hv_isolation_type_tdx())
+		goto skip_hypercall_pg_init;
+
 	hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START,
 			VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX,
 			VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
@@ -471,6 +475,7 @@ void __init hyperv_init(void)
 		wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 	}
 
+skip_hypercall_pg_init:
 	/*
 	 * hyperv_init() is called before LAPIC is initialized: see
 	 * apic_intr_mode_init() -> x86_platform.apic_post_init() and
@@ -606,6 +611,9 @@ bool hv_is_hyperv_initialized(void)
 	if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 		return false;
 
+	/* A TDX guest uses the GHCI call rather than hv_hypercall_pg. */
+	if (hv_isolation_type_tdx())
+		return true;
 	/*
 	 * Verify that earlier initialization succeeded by checking
 	 * that the hypercall page is setup
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 9d593ab2be26..650b4fae2fd8 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -9,7 +9,7 @@
 #include <asm/hyperv-tlfs.h>
 #include <asm/nospec-branch.h>
 #include <asm/paravirt.h>
-#include <asm/mshyperv.h>
+#include <asm-generic/ms_hyperv_info.h>
 
 union hv_ghcb;
 
@@ -48,6 +48,18 @@ static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
 	u64 hv_status;
 
 #ifdef CONFIG_X86_64
+#if CONFIG_INTEL_TDX_GUEST
+	if (hv_isolation_type_tdx()) {
+		if (input_address)
+			input_address += ms_hyperv.shared_gpa_boundary;
+
+		if (output_address)
+			output_address += ms_hyperv.shared_gpa_boundary;
+
+		return __tdx_ms_hv_hypercall(control, output_address,
+					     input_address);
+	}
+#endif
 	if (!hv_hypercall_pg)
 		return U64_MAX;
 
@@ -85,6 +97,11 @@ static inline u64 hv_do_fast_hypercall8(u16 code, u64 input1)
 	u64 hv_status, control = (u64)code | HV_HYPERCALL_FAST_BIT;
 
 #ifdef CONFIG_X86_64
+#if CONFIG_INTEL_TDX_GUEST
+	if (hv_isolation_type_tdx())
+		return __tdx_ms_hv_hypercall(control, 0, input1);
+#endif
+
 	{
 		__asm__ __volatile__(CALL_NOSPEC
 				     : "=a" (hv_status), ASM_CALL_CONSTRAINT,
@@ -116,6 +133,11 @@ static inline u64 hv_do_fast_hypercall16(u16 code, u64 input1, u64 input2)
 	u64 hv_status, control = (u64)code | HV_HYPERCALL_FAST_BIT;
 
 #ifdef CONFIG_X86_64
+#if CONFIG_INTEL_TDX_GUEST
+	if (hv_isolation_type_tdx())
+		return __tdx_ms_hv_hypercall(control, input2, input1);
+#endif
+
 	{
 		__asm__ __volatile__("mov %4, %%r8\n"
 				     CALL_NOSPEC
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 9ad0b0abf0e0..dddccdbc5526 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -349,6 +349,8 @@ static void __init ms_hyperv_init_platform(void)
 
 			case HV_ISOLATION_TYPE_TDX:
 				static_branch_enable(&isolation_type_tdx);
+
+				ms_hyperv.shared_gpa_boundary = cc_mkdec(0);
 				break;
 
 			default:
diff --git a/include/asm-generic/ms_hyperv_info.h b/include/asm-generic/ms_hyperv_info.h
new file mode 100644
index 000000000000..734583dfea99
--- /dev/null
+++ b/include/asm-generic/ms_hyperv_info.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _ASM_GENERIC_MS_HYPERV_INFO_H
+#define _ASM_GENERIC_MS_HYPERV_INFO_H
+
+struct ms_hyperv_info {
+	u32 features;
+	u32 priv_high;
+	u32 misc_features;
+	u32 hints;
+	u32 nested_features;
+	u32 max_vp_index;
+	u32 max_lp_index;
+	u32 isolation_config_a;
+	union {
+		u32 isolation_config_b;
+		struct {
+			u32 cvm_type : 4;
+			u32 reserved1 : 1;
+			u32 shared_gpa_boundary_active : 1;
+			u32 shared_gpa_boundary_bits : 6;
+			u32 reserved2 : 20;
+		};
+	};
+	u64 shared_gpa_boundary;
+};
+extern struct ms_hyperv_info ms_hyperv;
+
+#endif
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index bfb9eb9d7215..2ae3e4e4256b 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -25,29 +25,7 @@
 #include <linux/nmi.h>
 #include <asm/ptrace.h>
 #include <asm/hyperv-tlfs.h>
-
-struct ms_hyperv_info {
-	u32 features;
-	u32 priv_high;
-	u32 misc_features;
-	u32 hints;
-	u32 nested_features;
-	u32 max_vp_index;
-	u32 max_lp_index;
-	u32 isolation_config_a;
-	union {
-		u32 isolation_config_b;
-		struct {
-			u32 cvm_type : 4;
-			u32 reserved1 : 1;
-			u32 shared_gpa_boundary_active : 1;
-			u32 shared_gpa_boundary_bits : 6;
-			u32 reserved2 : 20;
-		};
-	};
-	u64 shared_gpa_boundary;
-};
-extern struct ms_hyperv_info ms_hyperv;
+#include <asm-generic/ms_hyperv_info.h>
 
 extern void * __percpu *hyperv_pcpu_input_arg;
 extern void * __percpu *hyperv_pcpu_output_arg;
-- 
2.25.1