From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH 3/3] KVM: Add KVM_VCPU_GET_REG_LIST/KVM_CAP_REG_LIST.
Date: Thu, 11 Oct 2012 18:41:47 +1030
Message-ID: <87lifd77i4.fsf@rustcorp.com.au>
References: <1346831926-31820-1-git-send-email-rusty.russell@linaro.org> <1346831926-31820-4-git-send-email-rusty.russell@linaro.org> <20121010181239.GA10649@amt.cnet>
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Cc: kvm@vger.kernel.org, Avi Kivity <avi@redhat.com>,
	Christoffer Dall <c.dall@virtualopensystems.com>,
	Alexander Graf <agraf@suse.de>,
	Peter Maydell <peter.maydell@linaro.org>
To: Marcelo Tosatti <mtosatti@redhat.com>,
	Rusty Russell <rusty.russell@linaro.org>
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Marcelo Tosatti <mtosatti@redhat.com> writes:
> On Wed, Sep 05, 2012 at 05:28:46PM +0930, Rusty Russell wrote:
...
>> +struct kvm_reg_list {
>> +	__u64 n; /* number of registers in reg[] */
>> +	__u64 reg[0];
>> +};
>>
>> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
>> index 169a001..453fe93 100644
>> --- a/virt/kvm/kvm_main.c
>> +++ b/virt/kvm/kvm_main.c
>> @@ -2082,6 +2082,23 @@ out_free2:
>>  		break;
>>  	}
>>  #endif
>> +#ifdef KVM_HAVE_REG_LIST
>> +	case KVM_VCPU_GET_REG_LIST: {
>> +		struct kvm_reg_list __user *user_list = argp;
>> +		struct kvm_reg_list reg_list;
>> +		unsigned n;
>> +
>> +		if (copy_from_user(&reg_list, user_list, sizeof reg_list))
>> +			return -EFAULT;
>> +		n = reg_list.n;
>> +		reg_list.n = kvm_arch_num_regs(vcpu);
>
> The code does not actually support more than 2^32 registers, does it?
> Why "__u64 n" ?

Well, the interface is simpler, and the alignment issues vanish.

kvm_arch_num_regs could return a 64-bit number in future if we want to
get completely insane :)

Cheers,
Rusty.