From: Tianyu Lan <redacted>

Hyper-V exposes GHCB page via SEV ES GHCB MSR for SNP guest
to communicate with hypervisor. Map GHCB page for all
cpus to read/write MSR register and submit hvcall request
via GHCB.

Signed-off-by: Tianyu Lan <redacted>
---
 arch/x86/hyperv/hv_init.c       | 60 ++++++++++++++++++++++++++++++---
 arch/x86/include/asm/mshyperv.h |  2 ++
 include/asm-generic/mshyperv.h  |  2 ++
 3 files changed, 60 insertions(+), 4 deletions(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index bb0ae4b5c00f..dc74d01cb859 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c

@@ -60,6 +60,9 @@ static int hv_cpu_init(unsigned int cpu)
 	struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
 	void **input_arg;
 	struct page *pg;
+	u64 ghcb_gpa;
+	void *ghcb_va;
+	void **ghcb_base;