Patchwork [v8,5/9] KVM: arm/arm64: preserve host MDCR_EL2 value

login
register
mail settings
Submitter Amit Daniel Kachhap
Date April 2, 2019, 2:27 a.m.
Message ID <1554172037-4516-6-git-send-email-amit.kachhap@arm.com>
Download mbox | patch
Permalink /patch/763159/
State New
Headers show

Comments

Amit Daniel Kachhap - April 2, 2019, 2:27 a.m.
Save host MDCR_EL2 value during kvm HYP initialisation and restore
after every switch from host to guest. There should not be any
change in functionality due to this.

The value of mdcr_el2 is now stored in struct kvm_cpu_context as
both host and guest can now use this field in a common way.

Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Christoffer Dall <christoffer.dall@arm.com>
Cc: kvmarm@lists.cs.columbia.edu
---

Changes since v7:
* Removed unused function __kvm_get_mdcr_el2 [Kristina].

 arch/arm/include/asm/kvm_host.h   |  1 -
 arch/arm64/include/asm/kvm_asm.h  |  2 --
 arch/arm64/include/asm/kvm_host.h |  6 ++----
 arch/arm64/include/asm/kvm_hyp.h  |  2 +-
 arch/arm64/kvm/debug.c            | 28 ++++++----------------------
 arch/arm64/kvm/hyp/debug-sr.c     |  5 -----
 arch/arm64/kvm/hyp/switch.c       | 18 +++++-------------
 arch/arm64/kvm/hyp/sysreg-sr.c    |  8 +++++++-
 virt/kvm/arm/arm.c                |  1 -
 9 files changed, 21 insertions(+), 50 deletions(-)
Dave Martin - April 5, 2019, 11:02 a.m.
On Tue, Apr 02, 2019 at 07:57:13AM +0530, Amit Daniel Kachhap wrote:
> Save host MDCR_EL2 value during kvm HYP initialisation and restore
> after every switch from host to guest. There should not be any
> change in functionality due to this.
> 
> The value of mdcr_el2 is now stored in struct kvm_cpu_context as
> both host and guest can now use this field in a common way.
> 
> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
> Acked-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Christoffer Dall <christoffer.dall@arm.com>
> Cc: kvmarm@lists.cs.columbia.edu
> ---
> 
> Changes since v7:
> * Removed unused function __kvm_get_mdcr_el2 [Kristina].
> 
>  arch/arm/include/asm/kvm_host.h   |  1 -
>  arch/arm64/include/asm/kvm_asm.h  |  2 --
>  arch/arm64/include/asm/kvm_host.h |  6 ++----
>  arch/arm64/include/asm/kvm_hyp.h  |  2 +-
>  arch/arm64/kvm/debug.c            | 28 ++++++----------------------
>  arch/arm64/kvm/hyp/debug-sr.c     |  5 -----
>  arch/arm64/kvm/hyp/switch.c       | 18 +++++-------------
>  arch/arm64/kvm/hyp/sysreg-sr.c    |  8 +++++++-
>  virt/kvm/arm/arm.c                |  1 -
>  9 files changed, 21 insertions(+), 50 deletions(-)
> 
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index 6d0aac4..a928565 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -343,7 +343,6 @@ static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
>  static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
>  static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
>  
> -static inline void kvm_arm_init_debug(void) {}
>  static inline void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) {}
>  static inline void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) {}
>  static inline void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu) {}
> diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
> index a68205c..a15ba55 100644
> --- a/arch/arm64/include/asm/kvm_asm.h
> +++ b/arch/arm64/include/asm/kvm_asm.h
> @@ -78,8 +78,6 @@ extern u64 __vgic_v3_read_vmcr(void);
>  extern void __vgic_v3_write_vmcr(u32 vmcr);
>  extern void __vgic_v3_init_lrs(void);
>  
> -extern u32 __kvm_get_mdcr_el2(void);
> -
>  extern void __kvm_populate_host_regs(void);
>  
>  /*
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 3b09fd0..e3ccd7b 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -211,6 +211,8 @@ struct kvm_cpu_context {
>  
>  	/* HYP host/guest configuration */
>  	u64 hcr_el2;
> +	u32 mdcr_el2;
> +
>  	struct kvm_vcpu *__hyp_running_vcpu;
>  };
>  
> @@ -226,9 +228,6 @@ struct vcpu_reset_state {
>  struct kvm_vcpu_arch {
>  	struct kvm_cpu_context ctxt;
>  
> -	/* HYP configuration */
> -	u32 mdcr_el2;
> -
>  	/* Exception Information */
>  	struct kvm_vcpu_fault_info fault;
>  
> @@ -498,7 +497,6 @@ static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
>  static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
>  static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
>  
> -void kvm_arm_init_debug(void);
>  void kvm_arm_setup_debug(struct kvm_vcpu *vcpu);
>  void kvm_arm_clear_debug(struct kvm_vcpu *vcpu);
>  void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu);
> diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
> index 4da765f..7fcde8a 100644
> --- a/arch/arm64/include/asm/kvm_hyp.h
> +++ b/arch/arm64/include/asm/kvm_hyp.h
> @@ -152,7 +152,7 @@ void __fpsimd_restore_state(struct user_fpsimd_state *fp_regs);
>  bool __fpsimd_enabled(void);
>  
>  void activate_traps_vhe_load(struct kvm_vcpu *vcpu);
> -void deactivate_traps_vhe_put(void);
> +void deactivate_traps_vhe_put(struct kvm_vcpu *vcpu);
>  
>  u64 __guest_enter(struct kvm_vcpu *vcpu, struct kvm_cpu_context *host_ctxt);
>  void __noreturn __hyp_do_panic(unsigned long, ...);
> diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c
> index fd917d6..99dc0a4 100644
> --- a/arch/arm64/kvm/debug.c
> +++ b/arch/arm64/kvm/debug.c
> @@ -32,8 +32,6 @@
>  				DBG_MDSCR_KDE | \
>  				DBG_MDSCR_MDE)
>  
> -static DEFINE_PER_CPU(u32, mdcr_el2);
> -
>  /**
>   * save/restore_guest_debug_regs
>   *
> @@ -65,21 +63,6 @@ static void restore_guest_debug_regs(struct kvm_vcpu *vcpu)
>  }
>  
>  /**
> - * kvm_arm_init_debug - grab what we need for debug
> - *
> - * Currently the sole task of this function is to retrieve the initial
> - * value of mdcr_el2 so we can preserve MDCR_EL2.HPMN which has
> - * presumably been set-up by some knowledgeable bootcode.
> - *
> - * It is called once per-cpu during CPU hyp initialisation.
> - */
> -
> -void kvm_arm_init_debug(void)
> -{
> -	__this_cpu_write(mdcr_el2, kvm_call_hyp_ret(__kvm_get_mdcr_el2));
> -}
> -
> -/**
>   * kvm_arm_reset_debug_ptr - reset the debug ptr to point to the vcpu state
>   */
>  
> @@ -111,6 +94,7 @@ void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu)
>  
>  void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
>  {
> +	kvm_cpu_context_t *host_cxt = this_cpu_ptr(&kvm_host_cpu_state);
>  	bool trap_debug = !(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY);
>  	unsigned long mdscr;
>  
> @@ -120,8 +104,8 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
>  	 * This also clears MDCR_EL2_E2PB_MASK to disable guest access
>  	 * to the profiling buffer.
>  	 */
> -	vcpu->arch.mdcr_el2 = __this_cpu_read(mdcr_el2) & MDCR_EL2_HPMN_MASK;
> -	vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM |
> +	vcpu->arch.ctxt.mdcr_el2 = host_cxt->mdcr_el2 & MDCR_EL2_HPMN_MASK;
> +	vcpu->arch.ctxt.mdcr_el2 |= (MDCR_EL2_TPM |
>  				MDCR_EL2_TPMS |
>  				MDCR_EL2_TPMCR |
>  				MDCR_EL2_TDRA |
> @@ -130,7 +114,7 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
>  	/* Is Guest debugging in effect? */
>  	if (vcpu->guest_debug) {
>  		/* Route all software debug exceptions to EL2 */
> -		vcpu->arch.mdcr_el2 |= MDCR_EL2_TDE;
> +		vcpu->arch.ctxt.mdcr_el2 |= MDCR_EL2_TDE;
>  
>  		/* Save guest debug state */
>  		save_guest_debug_regs(vcpu);
> @@ -202,13 +186,13 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
>  
>  	/* Trap debug register access */
>  	if (trap_debug)
> -		vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA;
> +		vcpu->arch.ctxt.mdcr_el2 |= MDCR_EL2_TDA;
>  
>  	/* If KDE or MDE are set, perform a full save/restore cycle. */
>  	if (vcpu_read_sys_reg(vcpu, MDSCR_EL1) & (DBG_MDSCR_KDE | DBG_MDSCR_MDE))
>  		vcpu->arch.flags |= KVM_ARM64_DEBUG_DIRTY;
>  
> -	trace_kvm_arm_set_dreg32("MDCR_EL2", vcpu->arch.mdcr_el2);
> +	trace_kvm_arm_set_dreg32("MDCR_EL2", vcpu->arch.ctxt.mdcr_el2);
>  	trace_kvm_arm_set_dreg32("MDSCR_EL1", vcpu_read_sys_reg(vcpu, MDSCR_EL1));
>  }
>  
> diff --git a/arch/arm64/kvm/hyp/debug-sr.c b/arch/arm64/kvm/hyp/debug-sr.c
> index 5000976..f49a3f7 100644
> --- a/arch/arm64/kvm/hyp/debug-sr.c
> +++ b/arch/arm64/kvm/hyp/debug-sr.c
> @@ -198,8 +198,3 @@ void __hyp_text __debug_switch_to_host(struct kvm_vcpu *vcpu)
>  
>  	vcpu->arch.flags &= ~KVM_ARM64_DEBUG_DIRTY;
>  }
> -
> -u32 __hyp_text __kvm_get_mdcr_el2(void)
> -{
> -	return read_sysreg(mdcr_el2);
> -}
> diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
> index f5cefa1..fe76e24 100644
> --- a/arch/arm64/kvm/hyp/switch.c
> +++ b/arch/arm64/kvm/hyp/switch.c
> @@ -84,7 +84,7 @@ static void __hyp_text __activate_traps_common(struct kvm_vcpu *vcpu)
>  	 */
>  	write_sysreg(0, pmselr_el0);
>  	write_sysreg(ARMV8_PMU_USERENR_MASK, pmuserenr_el0);
> -	write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2);
> +	write_sysreg(vcpu->arch.ctxt.mdcr_el2, mdcr_el2);
>  }
>  
>  static void __hyp_text __deactivate_traps_common(void)
> @@ -161,15 +161,11 @@ NOKPROBE_SYMBOL(deactivate_traps_vhe);
>  
>  static void __hyp_text __deactivate_traps_nvhe(struct kvm_cpu_context *host_ctxt)
>  {
> -	u64 mdcr_el2 = read_sysreg(mdcr_el2);
>  	struct kvm_cpu_context *hyp_host_ctxt = kern_hyp_va(host_ctxt);
>  
>  	__deactivate_traps_common();
>  
> -	mdcr_el2 &= MDCR_EL2_HPMN_MASK;
> -	mdcr_el2 |= MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT;
> -
> -	write_sysreg(mdcr_el2, mdcr_el2);
> +	write_sysreg(hyp_host_ctxt->mdcr_el2, mdcr_el2);
>  	write_sysreg(hyp_host_ctxt->hcr_el2, hcr_el2);
>  	write_sysreg(CPTR_EL2_DEFAULT, cptr_el2);
>  }
> @@ -199,15 +195,11 @@ void activate_traps_vhe_load(struct kvm_vcpu *vcpu)
>  	__activate_traps_common(vcpu);
>  }
>  
> -void deactivate_traps_vhe_put(void)
> +void deactivate_traps_vhe_put(struct kvm_vcpu *vcpu)
>  {
> -	u64 mdcr_el2 = read_sysreg(mdcr_el2);
> -
> -	mdcr_el2 &= MDCR_EL2_HPMN_MASK |
> -		    MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT |
> -		    MDCR_EL2_TPMS;
> +	struct kvm_cpu_context *host_ctxt = vcpu->arch.host_cpu_context;
>  
> -	write_sysreg(mdcr_el2, mdcr_el2);
> +	write_sysreg(host_ctxt->mdcr_el2, mdcr_el2);
>  
>  	__deactivate_traps_common();
>  }
> diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c
> index 277f82b..6afd309 100644
> --- a/arch/arm64/kvm/hyp/sysreg-sr.c
> +++ b/arch/arm64/kvm/hyp/sysreg-sr.c
> @@ -298,7 +298,7 @@ void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu)
>  	if (!has_vhe())
>  		return;
>  
> -	deactivate_traps_vhe_put();
> +	deactivate_traps_vhe_put(vcpu);
>  
>  	__sysreg_save_el1_state(guest_ctxt);
>  	__sysreg_save_user_state(guest_ctxt);
> @@ -333,4 +333,10 @@ void __hyp_text __kvm_populate_host_regs(void)
>  
>  	host_ctxt = __hyp_this_cpu_ptr(kvm_host_cpu_state);
>  	host_ctxt->hcr_el2 = read_sysreg(hcr_el2);
> +	/*
> +	 * Retrieve the initial value of mdcr_el2 so we can preserve
> +	 * MDCR_EL2.HPMN which has presumably been set-up by some
> +	 * knowledgeable bootcode.
> +	 */
> +	host_ctxt->mdcr_el2 = read_sysreg(mdcr_el2);
>  }
> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
> index e8c2ee6..58de0ca 100644
> --- a/virt/kvm/arm/arm.c
> +++ b/virt/kvm/arm/arm.c
> @@ -1322,7 +1322,6 @@ static void cpu_hyp_reinit(void)
>  	else
>  		cpu_init_hyp_mode(NULL);
>  
> -	kvm_arm_init_debug();
>  	cpu_init_host_ctxt();
>  
>  	if (vgic_present)

Looks reasonable overall.

I was wondering whether it would make sense to move some masking into
__kvm_populate_host_regs(), but probably not.

Reviewed-by: Dave Martin <Dave.Martin@arm.com>

Cheers
---Dave


> -- 
> 2.7.4
> 
> _______________________________________________
> kvmarm mailing list
> kvmarm@lists.cs.columbia.edu
> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
Amit Daniel Kachhap - April 8, 2019, 4:39 a.m.
Hi,

On 4/5/19 4:32 PM, Dave Martin wrote:
> On Tue, Apr 02, 2019 at 07:57:13AM +0530, Amit Daniel Kachhap wrote:
>> Save host MDCR_EL2 value during kvm HYP initialisation and restore
>> after every switch from host to guest. There should not be any
>> change in functionality due to this.
>>
>> The value of mdcr_el2 is now stored in struct kvm_cpu_context as
>> both host and guest can now use this field in a common way.
>>
>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
>> Acked-by: Mark Rutland <mark.rutland@arm.com>
>> Cc: Marc Zyngier <marc.zyngier@arm.com>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Christoffer Dall <christoffer.dall@arm.com>
>> Cc: kvmarm@lists.cs.columbia.edu
>> ---
>>
>> Changes since v7:
>> * Removed unused function __kvm_get_mdcr_el2 [Kristina].
>>
>>   arch/arm/include/asm/kvm_host.h   |  1 -
>>   arch/arm64/include/asm/kvm_asm.h  |  2 --
>>   arch/arm64/include/asm/kvm_host.h |  6 ++----
>>   arch/arm64/include/asm/kvm_hyp.h  |  2 +-
>>   arch/arm64/kvm/debug.c            | 28 ++++++----------------------
>>   arch/arm64/kvm/hyp/debug-sr.c     |  5 -----
>>   arch/arm64/kvm/hyp/switch.c       | 18 +++++-------------
>>   arch/arm64/kvm/hyp/sysreg-sr.c    |  8 +++++++-
>>   virt/kvm/arm/arm.c                |  1 -
>>   9 files changed, 21 insertions(+), 50 deletions(-)
>>
>> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
>> index 6d0aac4..a928565 100644
>> --- a/arch/arm/include/asm/kvm_host.h
>> +++ b/arch/arm/include/asm/kvm_host.h
>> @@ -343,7 +343,6 @@ static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
>>   static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
>>   static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
>>   
>> -static inline void kvm_arm_init_debug(void) {}
>>   static inline void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) {}
>>   static inline void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) {}
>>   static inline void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu) {}
>> diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
>> index a68205c..a15ba55 100644
>> --- a/arch/arm64/include/asm/kvm_asm.h
>> +++ b/arch/arm64/include/asm/kvm_asm.h
>> @@ -78,8 +78,6 @@ extern u64 __vgic_v3_read_vmcr(void);
>>   extern void __vgic_v3_write_vmcr(u32 vmcr);
>>   extern void __vgic_v3_init_lrs(void);
>>   
>> -extern u32 __kvm_get_mdcr_el2(void);
>> -
>>   extern void __kvm_populate_host_regs(void);
>>   
>>   /*
>> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
>> index 3b09fd0..e3ccd7b 100644
>> --- a/arch/arm64/include/asm/kvm_host.h
>> +++ b/arch/arm64/include/asm/kvm_host.h
>> @@ -211,6 +211,8 @@ struct kvm_cpu_context {
>>   
>>   	/* HYP host/guest configuration */
>>   	u64 hcr_el2;
>> +	u32 mdcr_el2;
>> +
>>   	struct kvm_vcpu *__hyp_running_vcpu;
>>   };
>>   
>> @@ -226,9 +228,6 @@ struct vcpu_reset_state {
>>   struct kvm_vcpu_arch {
>>   	struct kvm_cpu_context ctxt;
>>   
>> -	/* HYP configuration */
>> -	u32 mdcr_el2;
>> -
>>   	/* Exception Information */
>>   	struct kvm_vcpu_fault_info fault;
>>   
>> @@ -498,7 +497,6 @@ static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
>>   static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
>>   static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
>>   
>> -void kvm_arm_init_debug(void);
>>   void kvm_arm_setup_debug(struct kvm_vcpu *vcpu);
>>   void kvm_arm_clear_debug(struct kvm_vcpu *vcpu);
>>   void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu);
>> diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
>> index 4da765f..7fcde8a 100644
>> --- a/arch/arm64/include/asm/kvm_hyp.h
>> +++ b/arch/arm64/include/asm/kvm_hyp.h
>> @@ -152,7 +152,7 @@ void __fpsimd_restore_state(struct user_fpsimd_state *fp_regs);
>>   bool __fpsimd_enabled(void);
>>   
>>   void activate_traps_vhe_load(struct kvm_vcpu *vcpu);
>> -void deactivate_traps_vhe_put(void);
>> +void deactivate_traps_vhe_put(struct kvm_vcpu *vcpu);
>>   
>>   u64 __guest_enter(struct kvm_vcpu *vcpu, struct kvm_cpu_context *host_ctxt);
>>   void __noreturn __hyp_do_panic(unsigned long, ...);
>> diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c
>> index fd917d6..99dc0a4 100644
>> --- a/arch/arm64/kvm/debug.c
>> +++ b/arch/arm64/kvm/debug.c
>> @@ -32,8 +32,6 @@
>>   				DBG_MDSCR_KDE | \
>>   				DBG_MDSCR_MDE)
>>   
>> -static DEFINE_PER_CPU(u32, mdcr_el2);
>> -
>>   /**
>>    * save/restore_guest_debug_regs
>>    *
>> @@ -65,21 +63,6 @@ static void restore_guest_debug_regs(struct kvm_vcpu *vcpu)
>>   }
>>   
>>   /**
>> - * kvm_arm_init_debug - grab what we need for debug
>> - *
>> - * Currently the sole task of this function is to retrieve the initial
>> - * value of mdcr_el2 so we can preserve MDCR_EL2.HPMN which has
>> - * presumably been set-up by some knowledgeable bootcode.
>> - *
>> - * It is called once per-cpu during CPU hyp initialisation.
>> - */
>> -
>> -void kvm_arm_init_debug(void)
>> -{
>> -	__this_cpu_write(mdcr_el2, kvm_call_hyp_ret(__kvm_get_mdcr_el2));
>> -}
>> -
>> -/**
>>    * kvm_arm_reset_debug_ptr - reset the debug ptr to point to the vcpu state
>>    */
>>   
>> @@ -111,6 +94,7 @@ void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu)
>>   
>>   void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
>>   {
>> +	kvm_cpu_context_t *host_cxt = this_cpu_ptr(&kvm_host_cpu_state);
>>   	bool trap_debug = !(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY);
>>   	unsigned long mdscr;
>>   
>> @@ -120,8 +104,8 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
>>   	 * This also clears MDCR_EL2_E2PB_MASK to disable guest access
>>   	 * to the profiling buffer.
>>   	 */
>> -	vcpu->arch.mdcr_el2 = __this_cpu_read(mdcr_el2) & MDCR_EL2_HPMN_MASK;
>> -	vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM |
>> +	vcpu->arch.ctxt.mdcr_el2 = host_cxt->mdcr_el2 & MDCR_EL2_HPMN_MASK;
>> +	vcpu->arch.ctxt.mdcr_el2 |= (MDCR_EL2_TPM |
>>   				MDCR_EL2_TPMS |
>>   				MDCR_EL2_TPMCR |
>>   				MDCR_EL2_TDRA |
>> @@ -130,7 +114,7 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
>>   	/* Is Guest debugging in effect? */
>>   	if (vcpu->guest_debug) {
>>   		/* Route all software debug exceptions to EL2 */
>> -		vcpu->arch.mdcr_el2 |= MDCR_EL2_TDE;
>> +		vcpu->arch.ctxt.mdcr_el2 |= MDCR_EL2_TDE;
>>   
>>   		/* Save guest debug state */
>>   		save_guest_debug_regs(vcpu);
>> @@ -202,13 +186,13 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
>>   
>>   	/* Trap debug register access */
>>   	if (trap_debug)
>> -		vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA;
>> +		vcpu->arch.ctxt.mdcr_el2 |= MDCR_EL2_TDA;
>>   
>>   	/* If KDE or MDE are set, perform a full save/restore cycle. */
>>   	if (vcpu_read_sys_reg(vcpu, MDSCR_EL1) & (DBG_MDSCR_KDE | DBG_MDSCR_MDE))
>>   		vcpu->arch.flags |= KVM_ARM64_DEBUG_DIRTY;
>>   
>> -	trace_kvm_arm_set_dreg32("MDCR_EL2", vcpu->arch.mdcr_el2);
>> +	trace_kvm_arm_set_dreg32("MDCR_EL2", vcpu->arch.ctxt.mdcr_el2);
>>   	trace_kvm_arm_set_dreg32("MDSCR_EL1", vcpu_read_sys_reg(vcpu, MDSCR_EL1));
>>   }
>>   
>> diff --git a/arch/arm64/kvm/hyp/debug-sr.c b/arch/arm64/kvm/hyp/debug-sr.c
>> index 5000976..f49a3f7 100644
>> --- a/arch/arm64/kvm/hyp/debug-sr.c
>> +++ b/arch/arm64/kvm/hyp/debug-sr.c
>> @@ -198,8 +198,3 @@ void __hyp_text __debug_switch_to_host(struct kvm_vcpu *vcpu)
>>   
>>   	vcpu->arch.flags &= ~KVM_ARM64_DEBUG_DIRTY;
>>   }
>> -
>> -u32 __hyp_text __kvm_get_mdcr_el2(void)
>> -{
>> -	return read_sysreg(mdcr_el2);
>> -}
>> diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
>> index f5cefa1..fe76e24 100644
>> --- a/arch/arm64/kvm/hyp/switch.c
>> +++ b/arch/arm64/kvm/hyp/switch.c
>> @@ -84,7 +84,7 @@ static void __hyp_text __activate_traps_common(struct kvm_vcpu *vcpu)
>>   	 */
>>   	write_sysreg(0, pmselr_el0);
>>   	write_sysreg(ARMV8_PMU_USERENR_MASK, pmuserenr_el0);
>> -	write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2);
>> +	write_sysreg(vcpu->arch.ctxt.mdcr_el2, mdcr_el2);
>>   }
>>   
>>   static void __hyp_text __deactivate_traps_common(void)
>> @@ -161,15 +161,11 @@ NOKPROBE_SYMBOL(deactivate_traps_vhe);
>>   
>>   static void __hyp_text __deactivate_traps_nvhe(struct kvm_cpu_context *host_ctxt)
>>   {
>> -	u64 mdcr_el2 = read_sysreg(mdcr_el2);
>>   	struct kvm_cpu_context *hyp_host_ctxt = kern_hyp_va(host_ctxt);
>>   
>>   	__deactivate_traps_common();
>>   
>> -	mdcr_el2 &= MDCR_EL2_HPMN_MASK;
>> -	mdcr_el2 |= MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT;
>> -
>> -	write_sysreg(mdcr_el2, mdcr_el2);
>> +	write_sysreg(hyp_host_ctxt->mdcr_el2, mdcr_el2);
>>   	write_sysreg(hyp_host_ctxt->hcr_el2, hcr_el2);
>>   	write_sysreg(CPTR_EL2_DEFAULT, cptr_el2);
>>   }
>> @@ -199,15 +195,11 @@ void activate_traps_vhe_load(struct kvm_vcpu *vcpu)
>>   	__activate_traps_common(vcpu);
>>   }
>>   
>> -void deactivate_traps_vhe_put(void)
>> +void deactivate_traps_vhe_put(struct kvm_vcpu *vcpu)
>>   {
>> -	u64 mdcr_el2 = read_sysreg(mdcr_el2);
>> -
>> -	mdcr_el2 &= MDCR_EL2_HPMN_MASK |
>> -		    MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT |
>> -		    MDCR_EL2_TPMS;
>> +	struct kvm_cpu_context *host_ctxt = vcpu->arch.host_cpu_context;
>>   
>> -	write_sysreg(mdcr_el2, mdcr_el2);
>> +	write_sysreg(host_ctxt->mdcr_el2, mdcr_el2);
>>   
>>   	__deactivate_traps_common();
>>   }
>> diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c
>> index 277f82b..6afd309 100644
>> --- a/arch/arm64/kvm/hyp/sysreg-sr.c
>> +++ b/arch/arm64/kvm/hyp/sysreg-sr.c
>> @@ -298,7 +298,7 @@ void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu)
>>   	if (!has_vhe())
>>   		return;
>>   
>> -	deactivate_traps_vhe_put();
>> +	deactivate_traps_vhe_put(vcpu);
>>   
>>   	__sysreg_save_el1_state(guest_ctxt);
>>   	__sysreg_save_user_state(guest_ctxt);
>> @@ -333,4 +333,10 @@ void __hyp_text __kvm_populate_host_regs(void)
>>   
>>   	host_ctxt = __hyp_this_cpu_ptr(kvm_host_cpu_state);
>>   	host_ctxt->hcr_el2 = read_sysreg(hcr_el2);
>> +	/*
>> +	 * Retrieve the initial value of mdcr_el2 so we can preserve
>> +	 * MDCR_EL2.HPMN which has presumably been set-up by some
>> +	 * knowledgeable bootcode.
>> +	 */
>> +	host_ctxt->mdcr_el2 = read_sysreg(mdcr_el2);
>>   }
>> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
>> index e8c2ee6..58de0ca 100644
>> --- a/virt/kvm/arm/arm.c
>> +++ b/virt/kvm/arm/arm.c
>> @@ -1322,7 +1322,6 @@ static void cpu_hyp_reinit(void)
>>   	else
>>   		cpu_init_hyp_mode(NULL);
>>   
>> -	kvm_arm_init_debug();
>>   	cpu_init_host_ctxt();
>>   
>>   	if (vgic_present)
> 
> Looks reasonable overall.
> 
> I was wondering whether it would make sense to move some masking into
> __kvm_populate_host_regs(), but probably not.
> 
> Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Thanks for the review.

Thanks,
Amit D.
> 
> Cheers
> ---Dave
> 
> 
>> -- 
>> 2.7.4
>>
>> _______________________________________________
>> kvmarm mailing list
>> kvmarm@lists.cs.columbia.edu
>> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

Patch

diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 6d0aac4..a928565 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -343,7 +343,6 @@  static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
 static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
 
-static inline void kvm_arm_init_debug(void) {}
 static inline void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu) {}
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index a68205c..a15ba55 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -78,8 +78,6 @@  extern u64 __vgic_v3_read_vmcr(void);
 extern void __vgic_v3_write_vmcr(u32 vmcr);
 extern void __vgic_v3_init_lrs(void);
 
-extern u32 __kvm_get_mdcr_el2(void);
-
 extern void __kvm_populate_host_regs(void);
 
 /*
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 3b09fd0..e3ccd7b 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -211,6 +211,8 @@  struct kvm_cpu_context {
 
 	/* HYP host/guest configuration */
 	u64 hcr_el2;
+	u32 mdcr_el2;
+
 	struct kvm_vcpu *__hyp_running_vcpu;
 };
 
@@ -226,9 +228,6 @@  struct vcpu_reset_state {
 struct kvm_vcpu_arch {
 	struct kvm_cpu_context ctxt;
 
-	/* HYP configuration */
-	u32 mdcr_el2;
-
 	/* Exception Information */
 	struct kvm_vcpu_fault_info fault;
 
@@ -498,7 +497,6 @@  static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
 static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
 
-void kvm_arm_init_debug(void);
 void kvm_arm_setup_debug(struct kvm_vcpu *vcpu);
 void kvm_arm_clear_debug(struct kvm_vcpu *vcpu);
 void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
index 4da765f..7fcde8a 100644
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -152,7 +152,7 @@  void __fpsimd_restore_state(struct user_fpsimd_state *fp_regs);
 bool __fpsimd_enabled(void);
 
 void activate_traps_vhe_load(struct kvm_vcpu *vcpu);
-void deactivate_traps_vhe_put(void);
+void deactivate_traps_vhe_put(struct kvm_vcpu *vcpu);
 
 u64 __guest_enter(struct kvm_vcpu *vcpu, struct kvm_cpu_context *host_ctxt);
 void __noreturn __hyp_do_panic(unsigned long, ...);
diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c
index fd917d6..99dc0a4 100644
--- a/arch/arm64/kvm/debug.c
+++ b/arch/arm64/kvm/debug.c
@@ -32,8 +32,6 @@ 
 				DBG_MDSCR_KDE | \
 				DBG_MDSCR_MDE)
 
-static DEFINE_PER_CPU(u32, mdcr_el2);
-
 /**
  * save/restore_guest_debug_regs
  *
@@ -65,21 +63,6 @@  static void restore_guest_debug_regs(struct kvm_vcpu *vcpu)
 }
 
 /**
- * kvm_arm_init_debug - grab what we need for debug
- *
- * Currently the sole task of this function is to retrieve the initial
- * value of mdcr_el2 so we can preserve MDCR_EL2.HPMN which has
- * presumably been set-up by some knowledgeable bootcode.
- *
- * It is called once per-cpu during CPU hyp initialisation.
- */
-
-void kvm_arm_init_debug(void)
-{
-	__this_cpu_write(mdcr_el2, kvm_call_hyp_ret(__kvm_get_mdcr_el2));
-}
-
-/**
  * kvm_arm_reset_debug_ptr - reset the debug ptr to point to the vcpu state
  */
 
@@ -111,6 +94,7 @@  void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu)
 
 void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
 {
+	kvm_cpu_context_t *host_cxt = this_cpu_ptr(&kvm_host_cpu_state);
 	bool trap_debug = !(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY);
 	unsigned long mdscr;
 
@@ -120,8 +104,8 @@  void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
 	 * This also clears MDCR_EL2_E2PB_MASK to disable guest access
 	 * to the profiling buffer.
 	 */
-	vcpu->arch.mdcr_el2 = __this_cpu_read(mdcr_el2) & MDCR_EL2_HPMN_MASK;
-	vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM |
+	vcpu->arch.ctxt.mdcr_el2 = host_cxt->mdcr_el2 & MDCR_EL2_HPMN_MASK;
+	vcpu->arch.ctxt.mdcr_el2 |= (MDCR_EL2_TPM |
 				MDCR_EL2_TPMS |
 				MDCR_EL2_TPMCR |
 				MDCR_EL2_TDRA |
@@ -130,7 +114,7 @@  void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
 	/* Is Guest debugging in effect? */
 	if (vcpu->guest_debug) {
 		/* Route all software debug exceptions to EL2 */
-		vcpu->arch.mdcr_el2 |= MDCR_EL2_TDE;
+		vcpu->arch.ctxt.mdcr_el2 |= MDCR_EL2_TDE;
 
 		/* Save guest debug state */
 		save_guest_debug_regs(vcpu);
@@ -202,13 +186,13 @@  void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
 
 	/* Trap debug register access */
 	if (trap_debug)
-		vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA;
+		vcpu->arch.ctxt.mdcr_el2 |= MDCR_EL2_TDA;
 
 	/* If KDE or MDE are set, perform a full save/restore cycle. */
 	if (vcpu_read_sys_reg(vcpu, MDSCR_EL1) & (DBG_MDSCR_KDE | DBG_MDSCR_MDE))
 		vcpu->arch.flags |= KVM_ARM64_DEBUG_DIRTY;
 
-	trace_kvm_arm_set_dreg32("MDCR_EL2", vcpu->arch.mdcr_el2);
+	trace_kvm_arm_set_dreg32("MDCR_EL2", vcpu->arch.ctxt.mdcr_el2);
 	trace_kvm_arm_set_dreg32("MDSCR_EL1", vcpu_read_sys_reg(vcpu, MDSCR_EL1));
 }
 
diff --git a/arch/arm64/kvm/hyp/debug-sr.c b/arch/arm64/kvm/hyp/debug-sr.c
index 5000976..f49a3f7 100644
--- a/arch/arm64/kvm/hyp/debug-sr.c
+++ b/arch/arm64/kvm/hyp/debug-sr.c
@@ -198,8 +198,3 @@  void __hyp_text __debug_switch_to_host(struct kvm_vcpu *vcpu)
 
 	vcpu->arch.flags &= ~KVM_ARM64_DEBUG_DIRTY;
 }
-
-u32 __hyp_text __kvm_get_mdcr_el2(void)
-{
-	return read_sysreg(mdcr_el2);
-}
diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index f5cefa1..fe76e24 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -84,7 +84,7 @@  static void __hyp_text __activate_traps_common(struct kvm_vcpu *vcpu)
 	 */
 	write_sysreg(0, pmselr_el0);
 	write_sysreg(ARMV8_PMU_USERENR_MASK, pmuserenr_el0);
-	write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2);
+	write_sysreg(vcpu->arch.ctxt.mdcr_el2, mdcr_el2);
 }
 
 static void __hyp_text __deactivate_traps_common(void)
@@ -161,15 +161,11 @@  NOKPROBE_SYMBOL(deactivate_traps_vhe);
 
 static void __hyp_text __deactivate_traps_nvhe(struct kvm_cpu_context *host_ctxt)
 {
-	u64 mdcr_el2 = read_sysreg(mdcr_el2);
 	struct kvm_cpu_context *hyp_host_ctxt = kern_hyp_va(host_ctxt);
 
 	__deactivate_traps_common();
 
-	mdcr_el2 &= MDCR_EL2_HPMN_MASK;
-	mdcr_el2 |= MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT;
-
-	write_sysreg(mdcr_el2, mdcr_el2);
+	write_sysreg(hyp_host_ctxt->mdcr_el2, mdcr_el2);
 	write_sysreg(hyp_host_ctxt->hcr_el2, hcr_el2);
 	write_sysreg(CPTR_EL2_DEFAULT, cptr_el2);
 }
@@ -199,15 +195,11 @@  void activate_traps_vhe_load(struct kvm_vcpu *vcpu)
 	__activate_traps_common(vcpu);
 }
 
-void deactivate_traps_vhe_put(void)
+void deactivate_traps_vhe_put(struct kvm_vcpu *vcpu)
 {
-	u64 mdcr_el2 = read_sysreg(mdcr_el2);
-
-	mdcr_el2 &= MDCR_EL2_HPMN_MASK |
-		    MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT |
-		    MDCR_EL2_TPMS;
+	struct kvm_cpu_context *host_ctxt = vcpu->arch.host_cpu_context;
 
-	write_sysreg(mdcr_el2, mdcr_el2);
+	write_sysreg(host_ctxt->mdcr_el2, mdcr_el2);
 
 	__deactivate_traps_common();
 }
diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c
index 277f82b..6afd309 100644
--- a/arch/arm64/kvm/hyp/sysreg-sr.c
+++ b/arch/arm64/kvm/hyp/sysreg-sr.c
@@ -298,7 +298,7 @@  void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu)
 	if (!has_vhe())
 		return;
 
-	deactivate_traps_vhe_put();
+	deactivate_traps_vhe_put(vcpu);
 
 	__sysreg_save_el1_state(guest_ctxt);
 	__sysreg_save_user_state(guest_ctxt);
@@ -333,4 +333,10 @@  void __hyp_text __kvm_populate_host_regs(void)
 
 	host_ctxt = __hyp_this_cpu_ptr(kvm_host_cpu_state);
 	host_ctxt->hcr_el2 = read_sysreg(hcr_el2);
+	/*
+	 * Retrieve the initial value of mdcr_el2 so we can preserve
+	 * MDCR_EL2.HPMN which has presumably been set-up by some
+	 * knowledgeable bootcode.
+	 */
+	host_ctxt->mdcr_el2 = read_sysreg(mdcr_el2);
 }
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index e8c2ee6..58de0ca 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -1322,7 +1322,6 @@  static void cpu_hyp_reinit(void)
 	else
 		cpu_init_hyp_mode(NULL);
 
-	kvm_arm_init_debug();
 	cpu_init_host_ctxt();
 
 	if (vgic_present)