Re: [PATCH 2/7] Added ONE_REG interface for debug instruction

From: Alexander Graf <agraf@suse.de>
To: Bharat Bhushan <r65777@freescale.com>
Cc: <kvm-ppc@vger.kernel.org>, <kvm@vger.kernel.org>,
	<scottwood@freescale.com>,
	Bharat Bhushan <bharat.bhushan@freescale.com>
Subject: Re: [PATCH 2/7] Added ONE_REG interface for debug instruction
Date: Thu, 7 Mar 2013 14:07:34 +0100	[thread overview]
Message-ID: <F600EAB4-C9DC-47FF-B5F0-AAF1E7C86A3E@suse.de> (raw)
In-Reply-To: <1362024796-4237-3-git-send-email-bharat.bhushan@freescale.com>

On 28.02.2013, at 05:13, Bharat Bhushan wrote:

> This patch adds the one_reg interface to get the special instruction
> to be used for setting software breakpoint from userspace.
> 
> Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
> ---
> Documentation/virtual/kvm/api.txt     |    1 +
> arch/powerpc/include/asm/kvm_book3s.h |    1 +
> arch/powerpc/include/asm/kvm_booke.h  |    2 ++
> arch/powerpc/include/uapi/asm/kvm.h   |    4 ++++
> arch/powerpc/kvm/book3s.c             |    6 ++++++
> arch/powerpc/kvm/booke.c              |    6 ++++++
> 6 files changed, 20 insertions(+), 0 deletions(-)
> 
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index cce500a..dbfcc04 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -1766,6 +1766,7 @@ registers, find a list below:
>   PPC   | KVM_REG_PPC_TSR	| 32
>   PPC   | KVM_REG_PPC_OR_TSR	| 32
>   PPC   | KVM_REG_PPC_CLEAR_TSR	| 32
> +  PPC   | KVM_REG_PPC_DEBUG_INST| 32
> 
> 4.69 KVM_GET_ONE_REG
> 
> diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
> index 5a56e1c..36164cc 100644
> --- a/arch/powerpc/include/asm/kvm_book3s.h
> +++ b/arch/powerpc/include/asm/kvm_book3s.h
> @@ -458,6 +458,7 @@ static inline bool kvmppc_critical_section(struct kvm_vcpu *vcpu)
> #define OSI_SC_MAGIC_R4			0x77810F9B
> 
> #define INS_DCBZ			0x7c0007ec
> +#define INS_TW				0x7c000008

This one should be "trap", so TO needs to be 31. The instruction as it's here is a nop if I read the spec correctly.

Alex

> 
> /* LPIDs we support with this build -- runtime limit may be lower */
> #define KVMPPC_NR_LPIDS			(LPID_RSVD + 1)
> diff --git a/arch/powerpc/include/asm/kvm_booke.h b/arch/powerpc/include/asm/kvm_booke.h
> index b7cd335..d3c1eb3 100644
> --- a/arch/powerpc/include/asm/kvm_booke.h
> +++ b/arch/powerpc/include/asm/kvm_booke.h
> @@ -26,6 +26,8 @@
> /* LPIDs we support with this build -- runtime limit may be lower */
> #define KVMPPC_NR_LPIDS                        64
> 
> +#define KVMPPC_INST_EHPRIV	0x7c00021c
> +
> static inline void kvmppc_set_gpr(struct kvm_vcpu *vcpu, int num, ulong val)
> {
> 	vcpu->arch.gpr[num] = val;
> diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
> index ef072b1..c2ff99c 100644
> --- a/arch/powerpc/include/uapi/asm/kvm.h
> +++ b/arch/powerpc/include/uapi/asm/kvm.h
> @@ -422,4 +422,8 @@ struct kvm_get_htab_header {
> #define KVM_REG_PPC_CLEAR_TSR	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0x88)
> #define KVM_REG_PPC_TCR		(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0x89)
> #define KVM_REG_PPC_TSR		(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0x8a)
> +
> +/* Debugging: Special instruction for software breakpoint */
> +#define KVM_REG_PPC_DEBUG_INST	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0x8b)
> +
> #endif /* __LINUX_KVM_POWERPC_H */
> diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
> index a4b6452..975a401 100644
> --- a/arch/powerpc/kvm/book3s.c
> +++ b/arch/powerpc/kvm/book3s.c
> @@ -530,6 +530,12 @@ int kvm_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu, struct kvm_one_reg *reg)
> 			val = get_reg_val(reg->id, vcpu->arch.vscr.u[3]);
> 			break;
> #endif /* CONFIG_ALTIVEC */
> +		case KVM_REG_PPC_DEBUG_INST: {
> +			u32 opcode = INS_TW;
> +			r = copy_to_user((u32 __user *)(long)reg->addr,
> +					 &opcode, sizeof(u32));
> +			break;
> +		}
> 		default:
> 			r = -EINVAL;
> 			break;
> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
> index 8b553c0..a41cd6d 100644
> --- a/arch/powerpc/kvm/booke.c
> +++ b/arch/powerpc/kvm/booke.c
> @@ -1448,6 +1448,12 @@ int kvm_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu, struct kvm_one_reg *reg)
> 	case KVM_REG_PPC_TSR:
> 		r = put_user(vcpu->arch.tsr, (u32 __user *)(long)reg->addr);
> 		break;
> +	case KVM_REG_PPC_DEBUG_INST: {
> +		u32 opcode = KVMPPC_INST_EHPRIV;
> +		r = copy_to_user((u32 __user *)(long)reg->addr,
> +				 &opcode, sizeof(u32));
> +		break;
> +	}
> 	default:
> 		break;
> 	}
> -- 
> 1.7.0.4
> 
> 
> --
> To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html