[RFC PATCH V2 06/18] x86/hyperv: Use vmmcall to implement hvcall in sev-snp enlightened guest

From: Tianyu Lan
Date: Fri Nov 18 2022 - 22:47:33 EST


From: Tianyu Lan <tiala@xxxxxxxxxxxxx>

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

Signed-off-by: Tianyu Lan <tiala@xxxxxxxxxxxxx>
---
arch/x86/include/asm/mshyperv.h | 66 ++++++++++++++++++++++-----------
1 file changed, 45 insertions(+), 21 deletions(-)

diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 9b8c3f638845..28d5429e33c9 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -45,16 +45,25 @@ 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);
@@ -82,12 +91,18 @@ 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)
- : THUNK_TARGET(hv_hypercall_pg)
- : "cc", "r8", "r9", "r10", "r11");
+ : "=a" (hv_status), ASM_CALL_CONSTRAINT,
+ "+c" (control), "+d" (input1)
+ : THUNK_TARGET(hv_hypercall_pg)
+ : "cc", "r8", "r9", "r10", "r11");
}
#else
{
@@ -113,14 +128,21 @@ 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"
- CALL_NOSPEC
- : "=a" (hv_status), ASM_CALL_CONSTRAINT,
- "+c" (control), "+d" (input1)
- : "r" (input2),
- THUNK_TARGET(hv_hypercall_pg)
- : "cc", "r8", "r9", "r10", "r11");
+ "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,
+ "+c" (control), "+d" (input1)
+ : "r" (input2),
+ THUNK_TARGET(hv_hypercall_pg)
+ : "cc", "r8", "r9", "r10", "r11");
}
#else
{
@@ -177,6 +199,7 @@ int hv_map_ioapic_interrupt(int ioapic_id, bool level, int vcpu, int vector,
struct hv_interrupt_entry *entry);
int hv_unmap_ioapic_interrupt(int ioapic_id, struct hv_interrupt_entry *entry);
int hv_set_mem_host_visibility(unsigned long addr, int numpages, bool visible);
+int hv_snp_boot_ap(int cpu, unsigned long start_ip);

#ifdef CONFIG_AMD_MEM_ENCRYPT
void hv_ghcb_msr_write(u64 msr, u64 value);
@@ -191,6 +214,7 @@ static inline void hv_ghcb_terminate(unsigned int set, unsigned int reason) {}
#endif

extern bool hv_isolation_type_snp(void);
+extern bool hv_isolation_type_en_snp(void);

static inline bool hv_is_synic_reg(unsigned int reg)
{
--
2.25.1