KVM hypercall framework relies on alternative framework to patch the
VMCALL -> VMMCALL on AMD platform. If a hypercall is made before
apply_alternative() is called then it defaults to VMCALL. The approach
works fine on non SEV guest. A VMCALL would causes #UD, and hypervisor
will be able to decode the instruction and do the right things. But
when SEV is active, guest memory is encrypted with guest key and
hypervisor will not be able to decode the instruction bytes.
Add SEV specific hypercall3, it unconditionally uses VMMCALL. The hypercall
will be used by the SEV guest to notify encrypted pages to the hypervisor.
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: "Radim Krčmář" <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Tom Lendacky <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Brijesh Singh <[email protected]>
---
arch/x86/include/asm/kvm_para.h | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 5ed3cf1c3934..94e91c0bc2e0 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -84,6 +84,18 @@ static inline long kvm_hypercall4(unsigned int nr, unsigned long p1,
return ret;
}
+static inline long kvm_sev_hypercall3(unsigned int nr, unsigned long p1,
+ unsigned long p2, unsigned long p3)
+{
+ long ret;
+
+ asm volatile("vmmcall"
+ : "=a"(ret)
+ : "a"(nr), "b"(p1), "c"(p2), "d"(p3)
+ : "memory");
+ return ret;
+}
+
#ifdef CONFIG_KVM_GUEST
bool kvm_para_available(void);
unsigned int kvm_arch_para_features(void);
--
2.17.1