Re: [PATCH v8 2/2] s390/kvm: diagnose 0x318 sync and reset

[Janosch Frank <frankja@linux.ibm.com>]

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On 6/19/20 12:22 AM, Collin Walling wrote:
> DIAGNOSE 0x318 (diag318) sets information regarding the environment
> the VM is running in (Linux, z/VM, etc) and is observed via
> firmware/service events.
> 
> This is a privileged s390x instruction that must be intercepted by
> SIE. Userspace handles the instruction as well as migration. Data
> is communicated via VCPU register synchronization.
> 
> The Control Program Name Code (CPNC) is stored in the SIE block. The
> CPNC along with the Control Program Version Code (CPVC) are stored
> in the kvm_vcpu_arch struct.
> 
> The CPNC is shadowed/unshadowed in VSIE.
> 
> This data is reset on load normal and clear resets.
> 
> Signed-off-by: Collin Walling <walling@linux.ibm.com>

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

Could you extend the s390 kvm selftests sync_regs test with diag318 please?

I'd also like to have it added to the kvm unit tests. You can either do
that yourself or I'll add it when I go over my pending patches. Since we
can't retrieve these values from the VM, a simple check for the sclp
feature bit and an execution of the instruction would be enough.

> ---
>  arch/s390/include/asm/kvm_host.h |  4 +++-
>  arch/s390/include/uapi/asm/kvm.h |  5 ++++-
>  arch/s390/kvm/kvm-s390.c         | 11 ++++++++++-
>  arch/s390/kvm/vsie.c             |  3 +++
>  include/uapi/linux/kvm.h         |  1 +
>  5 files changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> index 3d554887794e..8bdf6f1607ca 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -260,7 +260,8 @@ struct kvm_s390_sie_block {
>  	__u32	scaol;			/* 0x0064 */
>  	__u8	sdf;			/* 0x0068 */
>  	__u8    epdx;			/* 0x0069 */
> -	__u8    reserved6a[2];		/* 0x006a */
> +	__u8	cpnc;			/* 0x006a */
> +	__u8	reserved6b;		/* 0x006b */
>  	__u32	todpr;			/* 0x006c */
>  #define GISA_FORMAT1 0x00000001
>  	__u32	gd;			/* 0x0070 */
> @@ -745,6 +746,7 @@ struct kvm_vcpu_arch {
>  	bool gs_enabled;
>  	bool skey_enabled;
>  	struct kvm_s390_pv_vcpu pv;
> +	union diag318_info diag318_info;
>  };
>  
>  struct kvm_vm_stat {
> diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
> index 436ec7636927..2ae1b660086c 100644
> --- a/arch/s390/include/uapi/asm/kvm.h
> +++ b/arch/s390/include/uapi/asm/kvm.h
> @@ -231,11 +231,13 @@ struct kvm_guest_debug_arch {
>  #define KVM_SYNC_GSCB   (1UL << 9)
>  #define KVM_SYNC_BPBC   (1UL << 10)
>  #define KVM_SYNC_ETOKEN (1UL << 11)
> +#define KVM_SYNC_DIAG318 (1UL << 12)
>  
>  #define KVM_SYNC_S390_VALID_FIELDS \
>  	(KVM_SYNC_PREFIX | KVM_SYNC_GPRS | KVM_SYNC_ACRS | KVM_SYNC_CRS | \
>  	 KVM_SYNC_ARCH0 | KVM_SYNC_PFAULT | KVM_SYNC_VRS | KVM_SYNC_RICCB | \
> -	 KVM_SYNC_FPRS | KVM_SYNC_GSCB | KVM_SYNC_BPBC | KVM_SYNC_ETOKEN)
> +	 KVM_SYNC_FPRS | KVM_SYNC_GSCB | KVM_SYNC_BPBC | KVM_SYNC_ETOKEN | \
> +	 KVM_SYNC_DIAG318)
>  
>  /* length and alignment of the sdnx as a power of two */
>  #define SDNXC 8
> @@ -254,6 +256,7 @@ struct kvm_sync_regs {
>  	__u64 pft;	/* pfault token [PFAULT] */
>  	__u64 pfs;	/* pfault select [PFAULT] */
>  	__u64 pfc;	/* pfault compare [PFAULT] */
> +	__u64 diag318;	/* diagnose 0x318 info */
>  	union {
>  		__u64 vrs[32][2];	/* vector registers (KVM_SYNC_VRS) */
>  		__u64 fprs[16];		/* fp registers (KVM_SYNC_FPRS) */
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index d0ff26d157bc..b05ad718b64b 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -545,6 +545,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_S390_AIS_MIGRATION:
>  	case KVM_CAP_S390_VCPU_RESETS:
>  	case KVM_CAP_SET_GUEST_DEBUG:
> +	case KVM_CAP_S390_DIAG318:
>  		r = 1;
>  		break;
>  	case KVM_CAP_S390_HPAGE_1M:
> @@ -3267,7 +3268,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
>  				    KVM_SYNC_ACRS |
>  				    KVM_SYNC_CRS |
>  				    KVM_SYNC_ARCH0 |
> -				    KVM_SYNC_PFAULT;
> +				    KVM_SYNC_PFAULT |
> +				    KVM_SYNC_DIAG318;
>  	kvm_s390_set_prefix(vcpu, 0);
>  	if (test_kvm_facility(vcpu->kvm, 64))
>  		vcpu->run->kvm_valid_regs |= KVM_SYNC_RICCB;
> @@ -3562,6 +3564,7 @@ static void kvm_arch_vcpu_ioctl_initial_reset(struct kvm_vcpu *vcpu)
>  		vcpu->arch.sie_block->pp = 0;
>  		vcpu->arch.sie_block->fpf &= ~FPF_BPBC;
>  		vcpu->arch.sie_block->todpr = 0;
> +		vcpu->arch.sie_block->cpnc = 0;
>  	}
>  }
>  
> @@ -3579,6 +3582,7 @@ static void kvm_arch_vcpu_ioctl_clear_reset(struct kvm_vcpu *vcpu)
>  
>  	regs->etoken = 0;
>  	regs->etoken_extension = 0;
> +	regs->diag318 = 0;
>  }
>  
>  int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
> @@ -4194,6 +4198,10 @@ static void sync_regs_fmt2(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
>  		if (vcpu->arch.pfault_token == KVM_S390_PFAULT_TOKEN_INVALID)
>  			kvm_clear_async_pf_completion_queue(vcpu);
>  	}
> +	if (kvm_run->kvm_dirty_regs & KVM_SYNC_DIAG318) {
> +		vcpu->arch.diag318_info.val = kvm_run->s.regs.diag318;
> +		vcpu->arch.sie_block->cpnc = vcpu->arch.diag318_info.cpnc;
> +	}
>  	/*
>  	 * If userspace sets the riccb (e.g. after migration) to a valid state,
>  	 * we should enable RI here instead of doing the lazy enablement.
> @@ -4295,6 +4303,7 @@ static void store_regs_fmt2(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
>  	kvm_run->s.regs.pp = vcpu->arch.sie_block->pp;
>  	kvm_run->s.regs.gbea = vcpu->arch.sie_block->gbea;
>  	kvm_run->s.regs.bpbc = (vcpu->arch.sie_block->fpf & FPF_BPBC) == FPF_BPBC;
> +	kvm_run->s.regs.diag318 = vcpu->arch.diag318_info.val;
>  	if (MACHINE_HAS_GS) {
>  		__ctl_set_bit(2, 4);
>  		if (vcpu->arch.gs_enabled)
> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
> index 9e9056cebfcf..ba83d0568bc7 100644
> --- a/arch/s390/kvm/vsie.c
> +++ b/arch/s390/kvm/vsie.c
> @@ -423,6 +423,8 @@ static void unshadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
>  		break;
>  	}
>  
> +	scb_o->cpnc = scb_s->cpnc;
> +
>  	if (scb_s->ihcpu != 0xffffU)
>  		scb_o->ihcpu = scb_s->ihcpu;
>  }
> @@ -548,6 +550,7 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
>  		scb_s->ecd |= scb_o->ecd & ECD_ETOKENF;
>  
>  	scb_s->hpid = HPID_VSIE;
> +	scb_s->cpnc = scb_o->cpnc;
>  
>  	prepare_ibc(vcpu, vsie_page);
>  	rc = shadow_crycb(vcpu, vsie_page);
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 4fdf30316582..35cdb4307904 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1031,6 +1031,7 @@ struct kvm_ppc_resize_hpt {
>  #define KVM_CAP_PPC_SECURE_GUEST 181
>  #define KVM_CAP_HALT_POLL 182
>  #define KVM_CAP_ASYNC_PF_INT 183
> +#define KVM_CAP_S390_DIAG318 184
>  
>  #ifdef KVM_CAP_IRQ_ROUTING
>  
> 



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