[RFC PATCH V3 04/16] x86/hyperv: Use vmmcall to implement Hyper-V hypercall in sev-snp enlightened guest

[Tianyu Lan <ltykernel@gmail.com>]

From: Tianyu Lan <tiala@microsoft.com>

In sev-snp enlightened guest, Hyper-V hypercall needs
to use vmmcall to trigger vmexit and notify hypervisor
to handle hypercall request.

Signed-off-by: Tianyu Lan <tiala@microsoft.com>
---
Change since RFC V2:
       * Fix indentation style
---
 arch/x86/include/asm/mshyperv.h | 44 ++++++++++++++++++++++++---------
 1 file changed, 33 insertions(+), 11 deletions(-)

diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 285df71150e4..1a4af0a4f29a 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -44,16 +44,25 @@ static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
 	u64 hv_status;
 
 #ifdef CONFIG_X86_64
-	if (!hv_hypercall_pg)
-		return U64_MAX;
+	if (hv_isolation_type_en_snp()) {
+		__asm__ __volatile__("mov %4, %%r8\n"
+				     "vmmcall"
+				     : "=a" (hv_status), ASM_CALL_CONSTRAINT,
+				       "+c" (control), "+d" (input_address)
+				     :  "r" (output_address)
+				     : "cc", "memory", "r8", "r9", "r10", "r11");
+	} else {
+		if (!hv_hypercall_pg)
+			return U64_MAX;
 
-	__asm__ __volatile__("mov %4, %%r8\n"
-			     CALL_NOSPEC
-			     : "=a" (hv_status), ASM_CALL_CONSTRAINT,
-			       "+c" (control), "+d" (input_address)
-			     :  "r" (output_address),
-				THUNK_TARGET(hv_hypercall_pg)
-			     : "cc", "memory", "r8", "r9", "r10", "r11");
+		__asm__ __volatile__("mov %4, %%r8\n"
+				     CALL_NOSPEC
+				     : "=a" (hv_status), ASM_CALL_CONSTRAINT,
+				       "+c" (control), "+d" (input_address)
+				     :  "r" (output_address),
+					THUNK_TARGET(hv_hypercall_pg)
+				     : "cc", "memory", "r8", "r9", "r10", "r11");
+	}
 #else
 	u32 input_address_hi = upper_32_bits(input_address);
 	u32 input_address_lo = lower_32_bits(input_address);
@@ -81,7 +90,13 @@ 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 (hv_isolation_type_en_snp()) {
+		__asm__ __volatile__(
+				"vmmcall"
+				: "=a" (hv_status), ASM_CALL_CONSTRAINT,
+				"+c" (control), "+d" (input1)
+				:: "cc", "r8", "r9", "r10", "r11");
+	} else {
 		__asm__ __volatile__(CALL_NOSPEC
 				     : "=a" (hv_status), ASM_CALL_CONSTRAINT,
 				       "+c" (control), "+d" (input1)
@@ -112,7 +127,14 @@ 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 (hv_isolation_type_en_snp()) {
+		__asm__ __volatile__("mov %4, %%r8\n"
+				     "vmmcall"
+				     : "=a" (hv_status), ASM_CALL_CONSTRAINT,
+				       "+c" (control), "+d" (input1)
+				     : "r" (input2)
+				     : "cc", "r8", "r9", "r10", "r11");
+	} else {
 		__asm__ __volatile__("mov %4, %%r8\n"
 				     CALL_NOSPEC
 				     : "=a" (hv_status), ASM_CALL_CONSTRAINT,
-- 
2.25.1