linux-kernel - [PATCH V2 1/9] x86/hyperv: Add sev-snp enlightened guest static key

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Message-Id: <20230627032248.2170007-2-ltykernel@gmail.com>
Date:   Mon, 26 Jun 2023 23:22:39 -0400
From:   Tianyu Lan <ltykernel@...il.com>
To:     kys@...rosoft.com, haiyangz@...rosoft.com, wei.liu@...nel.org,
        decui@...rosoft.com, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org,
        hpa@...or.com, daniel.lezcano@...aro.org, arnd@...db.de,
        michael.h.kelley@...rosoft.com
Cc:     Tianyu Lan <tiala@...rosoft.com>, linux-arch@...r.kernel.org,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
        vkuznets@...hat.com
Subject: [PATCH V2 1/9] x86/hyperv: Add sev-snp enlightened guest static key

From: Tianyu Lan <tiala@...rosoft.com>

Introduce static key isolation_type_en_snp for enlightened
sev-snp guest check.

Signed-off-by: Tianyu Lan <tiala@...rosoft.com>
---
 arch/x86/hyperv/ivm.c           | 11 +++++++++++
 arch/x86/include/asm/mshyperv.h |  3 +++
 arch/x86/kernel/cpu/mshyperv.c  |  9 +++++++--
 drivers/hv/hv_common.c          |  6 ++++++
 include/asm-generic/mshyperv.h  | 12 +++++++++---
 5 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index cc92388b7a99..5d3ee3124e00 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -409,3 +409,14 @@ bool hv_isolation_type_snp(void)
 {
 	return static_branch_unlikely(&isolation_type_snp);
 }
+
+DEFINE_STATIC_KEY_FALSE(isolation_type_en_snp);
+/*
+ * hv_isolation_type_en_snp - Check system runs in the AMD SEV-SNP based
+ * isolation enlightened VM.
+ */
+bool hv_isolation_type_en_snp(void)
+{
+	return static_branch_unlikely(&isolation_type_en_snp);
+}
+
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 49bb4f2bd300..31c476f4e656 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -26,6 +26,7 @@
 union hv_ghcb;
 
 DECLARE_STATIC_KEY_FALSE(isolation_type_snp);
+DECLARE_STATIC_KEY_FALSE(isolation_type_en_snp);
 
 typedef int (*hyperv_fill_flush_list_func)(
 		struct hv_guest_mapping_flush_list *flush,
@@ -45,6 +46,8 @@ extern void *hv_hypercall_pg;
 
 extern u64 hv_current_partition_id;
 
+extern bool hv_isolation_type_en_snp(void);
+
 extern union hv_ghcb * __percpu *hv_ghcb_pg;
 
 int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages);
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index c7969e806c64..5398fb2f4d39 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -402,8 +402,12 @@ static void __init ms_hyperv_init_platform(void)
 		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);
 
-		if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP)
+
+		if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) {
+			static_branch_enable(&isolation_type_en_snp);
+		} else if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP) {
 			static_branch_enable(&isolation_type_snp);
+		}
 	}
 
 	if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) {
@@ -473,7 +477,8 @@ static void __init ms_hyperv_init_platform(void)
 
 #if IS_ENABLED(CONFIG_HYPERV)
 	if ((hv_get_isolation_type() == HV_ISOLATION_TYPE_VBS) ||
-	    (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP))
+	    ((hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP) &&
+	    ms_hyperv.paravisor_present))
 		hv_vtom_init();
 	/*
 	 * Setup the hook to get control post apic initialization.
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index 542a1d53b303..4b4aa53c34c2 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -502,6 +502,12 @@ bool __weak hv_isolation_type_snp(void)
 }
 EXPORT_SYMBOL_GPL(hv_isolation_type_snp);
 
+bool __weak hv_isolation_type_en_snp(void)
+{
+	return false;
+}
+EXPORT_SYMBOL_GPL(hv_isolation_type_en_snp);
+
 void __weak hv_setup_vmbus_handler(void (*handler)(void))
 {
 }
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index 402a8c1c202d..6b5c41f90398 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -36,15 +36,21 @@ struct ms_hyperv_info {
 	u32 nested_features;
 	u32 max_vp_index;
 	u32 max_lp_index;
-	u32 isolation_config_a;
+	union {
+		u32 isolation_config_a;
+		struct {
+			u32 paravisor_present : 1;
+			u32 reserved_a1 : 31;
+		};
+	};
 	union {
 		u32 isolation_config_b;
 		struct {
 			u32 cvm_type : 4;
-			u32 reserved1 : 1;
+			u32 reserved_b1 : 1;
 			u32 shared_gpa_boundary_active : 1;
 			u32 shared_gpa_boundary_bits : 6;
-			u32 reserved2 : 20;
+			u32 reserved_b2 : 20;
 		};
 	};
 	u64 shared_gpa_boundary;
-- 
2.25.1