[RFC V2 PATCH 2/12] x86/HV: Initialize shared memory boundary in Isolation VM

[Tianyu Lan]

From: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>

Hyper-V exposes shared memory boundary via cpuid HYPERV_
CPUID_ISOLATION_CONFIG and store it in the shared_gpa_
boundary of ms_hyperv struct. This prepares to share
memory with host for AMD SEV SNP guest.

Signed-off-by: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>
---
 arch/x86/kernel/cpu/mshyperv.c |  2 ++
 include/asm-generic/mshyperv.h | 13 ++++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index e88bc296afca..aeafd4017c89 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -328,6 +328,8 @@ static void __init ms_hyperv_init_platform(void)
 	if (ms_hyperv.features_b & HV_ISOLATION) {
 		ms_hyperv.isolation_config_a = cpuid_eax(HYPERV_CPUID_ISOLATION_CONFIG);
 		ms_hyperv.isolation_config_b = cpuid_ebx(HYPERV_CPUID_ISOLATION_CONFIG);
+		ms_hyperv.shared_gpa_boundary =
+			(u64)1 << ms_hyperv.shared_gpa_boundary_bits;
 
 		pr_info("Hyper-V: Isolation Config: Group A 0x%x, Group B 0x%x\n",
 			ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b);
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index c6f4c5c20fb8..b73e201abc70 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -34,8 +34,19 @@ struct ms_hyperv_info {
 	u32 max_vp_index;
 	u32 max_lp_index;
 	u32 isolation_config_a;
-	u32 isolation_config_b;
+	union
+	{
+		u32 isolation_config_b;
+		struct {
+			u32 cvm_type : 4;
+			u32 Reserved11 : 1;
+			u32 shared_gpa_boundary_active : 1;
+			u32 shared_gpa_boundary_bits : 6;
+			u32 Reserved12 : 20;
+		};
+	};
 	void  __percpu **ghcb_base;
+	u64 shared_gpa_boundary;
 };
 extern struct ms_hyperv_info ms_hyperv;
 
-- 
2.25.1