On 8/13/2021 3:18 AM, Michael Kelley wrote:

From: Tianyu Lan <redacted> Sent: Monday, August 9, 2021 10:56 AM

quoted

Subject: [PATCH V3 02/13] x86/HV: Initialize shared memory boundary in the Isolation VM.

As with Patch 1, use the "x86/hyperv:" tag in the Subject line.

quoted

From: Tianyu Lan <redacted>

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 SNP guest.

Signed-off-by: Tianyu Lan <redacted>
---
  arch/x86/kernel/cpu/mshyperv.c |  2 ++
  include/asm-generic/mshyperv.h | 12 +++++++++++-
  2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 6b5835a087a3..2b7f396ef1a5 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c

@@ -313,6 +313,8 @@ static void __init ms_hyperv_init_platform(void)
  	if (ms_hyperv.priv_high & 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;

You could use BIT_ULL() here, but it's kind of a shrug.

Good suggestion. Thanks.

quoted

  		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 4269f3174e58..aa26d24a5ca9 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h

@@ -35,8 +35,18 @@ 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;

Any reason to name the reserved fields as "11" and "12"?  It
just looks a bit unusual.  And I'd suggest lowercase "r".

Yes, will update in the next version.

quoted

+		};
+	};
  	void  __percpu **ghcb_base;
+	u64 shared_gpa_boundary;
  };
  extern struct ms_hyperv_info ms_hyperv;

--
2.25.1