linux-kernel - [RFC V2 8/9] Introduce kvm module parameter global

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Date:   Tue,  1 Sep 2020 19:57:11 +0800
From:   yulei.kernel@...il.com
To:     pbonzini@...hat.com
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        sean.j.christopherson@...el.com, jmattson@...gle.com,
        junaids@...gle.com, bgardon@...gle.com, vkuznets@...hat.com,
        xiaoguangrong.eric@...il.com, kernellwp@...il.com,
        lihaiwei.kernel@...il.com, Yulei Zhang <yuleixzhang@...cent.com>
Subject: [RFC V2 8/9] Introduce kvm module parameter global_tdp to turn on the direct build EPT mode

From: Yulei Zhang <yuleixzhang@...cent.com>

Currently global_tdp is only supported on intel X86 system with ept
supported, and it will turn off the smm mode when enable global_tdp.

Signed-off-by: Yulei Zhang <yuleixzhang@...cent.com>
---
 arch/x86/include/asm/kvm_host.h |  4 ++++
 arch/x86/kvm/mmu/mmu.c          |  5 ++++-
 arch/x86/kvm/x86.c              | 11 ++++++++++-
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 429a50c89268..330cb254b34b 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1357,6 +1357,8 @@ extern u64  kvm_default_tsc_scaling_ratio;
 
 extern u64 kvm_mce_cap_supported;
 
+extern bool global_tdp;
+
 /*
  * EMULTYPE_NO_DECODE - Set when re-emulating an instruction (after completing
  *			userspace I/O) to indicate that the emulation context
@@ -1689,6 +1691,8 @@ static inline int kvm_cpu_get_apicid(int mps_cpu)
 #endif
 }
 
+inline bool boot_cpu_is_amd(void);
+
 #define put_smstate(type, buf, offset, val)                      \
 	*(type *)((buf) + (offset) - 0x7e00) = val
 
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index f03bf8efcefe..6639d9c7012e 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4573,7 +4573,7 @@ reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context)
 }
 EXPORT_SYMBOL_GPL(reset_shadow_zero_bits_mask);
 
-static inline bool boot_cpu_is_amd(void)
+inline bool boot_cpu_is_amd(void)
 {
 	WARN_ON_ONCE(!tdp_enabled);
 	return shadow_x_mask == 0;
@@ -6497,6 +6497,9 @@ int kvm_direct_tdp_populate_page_table(struct kvm *kvm, struct kvm_memory_slot *
 	kvm_pfn_t pfn;
 	int host_level;
 
+	if (!global_tdp)
+		return 0;
+
 	if (!kvm->arch.global_root_hpa) {
 		struct page *page;
 		WARN_ON(!tdp_enabled);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ee898003f22f..57d64f3239e1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -161,6 +161,9 @@ module_param(force_emulation_prefix, bool, S_IRUGO);
 int __read_mostly pi_inject_timer = -1;
 module_param(pi_inject_timer, bint, S_IRUGO | S_IWUSR);
 
+bool __read_mostly global_tdp;
+module_param_named(global_tdp, global_tdp, bool, S_IRUGO);
+
 #define KVM_NR_SHARED_MSRS 16
 
 struct kvm_shared_msrs_global {
@@ -3539,7 +3542,10 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		 * fringe case that is not enabled except via specific settings
 		 * of the module parameters.
 		 */
-		r = kvm_x86_ops.has_emulated_msr(MSR_IA32_SMBASE);
+		if (global_tdp)
+			r = 0;
+		else
+			r = kvm_x86_ops.has_emulated_msr(MSR_IA32_SMBASE);
 		break;
 	case KVM_CAP_VAPIC:
 		r = !kvm_x86_ops.cpu_has_accelerated_tpr();
@@ -9808,6 +9814,9 @@ int kvm_arch_hardware_setup(void *opaque)
 	if (r != 0)
 		return r;
 
+	if ((tdp_enabled == false) || boot_cpu_is_amd())
+		global_tdp = 0;
+
 	memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
 
 	if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
-- 
2.17.1