KVM: arm64: Make use of TWED feature

virt inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I40FGG
CVE: NA

-----------------------------

For HCR_EL2, TWEDEn(bit[59]) decides whether TWED is enabled, and
when the configurable delay is enabled, TWEDEL (bits[63:60]) encodes
the minimum delay in taking a trap of WFE caused by the TWE bit in
this register as 2^(TWEDEL + 8) cycles.

We use two kernel parameters "twed_enable" and "twedel" to configure
the register.
Signed-off-by: NZengruan Ye <yezengruan@huawei.com>
Signed-off-by: NJingyi Wang <wangjingyi11@huawei.com>
Reviewed-by: NKeqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/arm64/include/asm/kvm_arm.h

@@ -12,6 +12,7 @@
 #include <asm/types.h>
 
 /* Hyp Configuration Register (HCR) bits */
+#define HCR_TWEDEN	(UL(1) << 59)
 #define HCR_ATA		(UL(1) << 56)
 #define HCR_FWB		(UL(1) << 46)
 #define HCR_API		(UL(1) << 41)
@@ -56,6 +57,13 @@
 #define HCR_SWIO	(UL(1) << 1)
 #define HCR_VM		(UL(1) << 0)
 
+#ifdef CONFIG_ARM64_TWED
+#define HCR_TWEDEL_SHIFT	60
+#define HCR_TWEDEL_MAX		(UL(0xf))
+#define HCR_TWEDEL_MASK		(HCR_TWEDEL_MAX << HCR_TWEDEL_SHIFT)
+#define HCR_TWEDEL		(UL(1) << HCR_TWEDEL_SHIFT)
+#endif
+
 /*
  * The bits we set in HCR:
  * TLOR:	Trap LORegion register accesses

arch/arm64/include/asm/kvm_emulate.h

@@ -102,6 +102,33 @@ static inline void vcpu_set_wfx_traps(struct kvm_vcpu *vcpu)
 	vcpu->arch.hcr_el2 |= HCR_TWI;
 }
 
+#ifdef CONFIG_ARM64_TWED
+static inline void vcpu_twed_enable(struct kvm_vcpu *vcpu)
+{
+	vcpu->arch.hcr_el2 |= HCR_TWEDEN;
+}
+
+static inline void vcpu_twed_disable(struct kvm_vcpu *vcpu)
+{
+	vcpu->arch.hcr_el2 &= ~HCR_TWEDEN;
+}
+
+static inline void vcpu_set_twed(struct kvm_vcpu *vcpu)
+{
+	u64 delay = (u64)twedel;
+
+	if (delay > HCR_TWEDEL_MAX)
+		delay = HCR_TWEDEL_MAX;
+
+	vcpu->arch.hcr_el2 &= ~HCR_TWEDEL_MASK;
+	vcpu->arch.hcr_el2 |= (delay << HCR_TWEDEL_SHIFT);
+}
+#else
+static inline void vcpu_twed_enable(struct kvm_vcpu *vcpu) {};
+static inline void vcpu_twed_disable(struct kvm_vcpu *vcpu) {};
+static inline void vcpu_set_twed(struct kvm_vcpu *vcpu) {};
+#endif
+
 static inline void vcpu_ptrauth_enable(struct kvm_vcpu *vcpu)
 {
 	vcpu->arch.hcr_el2 |= (HCR_API | HCR_APK);

arch/arm64/include/asm/kvm_host.h

@@ -699,4 +699,12 @@ bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu);
 #define kvm_arm_vcpu_sve_finalized(vcpu) \
 	((vcpu)->arch.flags & KVM_ARM64_VCPU_SVE_FINALIZED)
 
+#ifdef CONFIG_ARM64_TWED
+#define use_twed() (has_twed() && twed_enable)
+extern bool twed_enable;
+extern unsigned int twedel;
+#else
+#define use_twed() (false)
+#endif
+
 #endif /* __ARM64_KVM_HOST_H__ */

arch/arm64/include/asm/virt.h

@@ -97,6 +97,11 @@ static __always_inline bool has_vhe(void)
 		return cpus_have_final_cap(ARM64_HAS_VIRT_HOST_EXTN);
 }
 
+static __always_inline bool has_twed(void)
+{
+	return cpus_have_const_cap(ARM64_HAS_TWED);
+}
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* ! __ASM__VIRT_H */

arch/arm64/kvm/arm.c

@@ -61,6 +61,14 @@ static bool vgic_present;
 static DEFINE_PER_CPU(unsigned char, kvm_arm_hardware_enabled);
 DEFINE_STATIC_KEY_FALSE(userspace_irqchip_in_use);
 
+#ifdef CONFIG_ARM64_TWED
+bool twed_enable = false;
+module_param(twed_enable, bool, S_IRUGO | S_IWUSR);
+
+unsigned int twedel = 0;
+module_param(twedel, uint, S_IRUGO | S_IWUSR);
+#endif
+
 int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
 {
 	return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
@@ -818,6 +826,13 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 
 		kvm_arm_setup_debug(vcpu);
 
+		if (use_twed()) {
+			vcpu_twed_enable(vcpu);
+			vcpu_set_twed(vcpu);
+		} else {
+			vcpu_twed_disable(vcpu);
+		}
+
 		/**************************************************************
 		 * Enter the guest
 		 */