linux-kernel - [RFC PATCH V4 01/17] x86/hyperv: Add sev-snp enlightened guest static key

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Date:   Mon,  3 Apr 2023 13:43:49 -0400
From:   Tianyu Lan <ltykernel@...il.com>
To:     luto@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org,
        hpa@...or.com, seanjc@...gle.com, pbonzini@...hat.com,
        jgross@...e.com, tiala@...rosoft.com, kirill@...temov.name,
        jiangshan.ljs@...group.com, peterz@...radead.org,
        ashish.kalra@....com, srutherford@...gle.com,
        akpm@...ux-foundation.org, anshuman.khandual@....com,
        pawan.kumar.gupta@...ux.intel.com, adrian.hunter@...el.com,
        daniel.sneddon@...ux.intel.com, alexander.shishkin@...ux.intel.com,
        sandipan.das@....com, ray.huang@....com, brijesh.singh@....com,
        michael.roth@....com, thomas.lendacky@....com,
        venu.busireddy@...cle.com, sterritt@...gle.com,
        tony.luck@...el.com, samitolvanen@...gle.com, fenghua.yu@...el.com
Cc:     pangupta@....com, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, linux-hyperv@...r.kernel.org,
        linux-arch@...r.kernel.org
Subject: [RFC PATCH V4 01/17] 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>
---
Change since RFC v3:
	* Remove some Hyper-V specific config setting
---
 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 ++++++
 4 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index 127d5b7b63de..368b2731950e 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 e3cef98a0142..2fa40c6ca99f 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -22,6 +22,7 @@
 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,
@@ -36,6 +37,8 @@ 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 ff348ebb6ae2..2f2dcb2370b6 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -403,8 +403,12 @@ 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) {
@@ -474,7 +478,8 @@ 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
+	     && !cc_platform_has(CC_ATTR_GUEST_SEV_SNP)))
 		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 6d40b6c7b23b..e3b04e978932 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -271,6 +271,12 @@ 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))
 {
 }
-- 
2.25.1