Re: [RFC PATCH v4 05/18] kvm: x86: add kvm_arch_vcpu_set_regs()

[Patrick Colp <patrick.colp@xxxxxxxxxx>]

On 2017-12-18 02:06 PM, Adalber Lazăr wrote:
> From: Adalbert Lazar <alazar@xxxxxxxxxxxxxxx>
>
> This is a version of kvm_arch_vcpu_ioctl_set_regs() which does not touch
> the exceptions vector.
>
> Signed-off-by: Mihai Donțu <mdontu@xxxxxxxxxxxxxxx>
> ---
>   arch/x86/kvm/x86.c       | 34 ++++++++++++++++++++++++++++++++++
>   include/linux/kvm_host.h |  1 +
>   2 files changed, 35 insertions(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index e1a3c2c6ec08..4b0c3692386d 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -7389,6 +7389,40 @@ int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
>   	return 0;
>   }
>   
> +/*
> + * Similar to kvm_arch_vcpu_ioctl_set_regs() but it does not reset
> + * the exceptions
> + */
> +void kvm_arch_vcpu_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
> +{
> +	vcpu->arch.emulate_regs_need_sync_from_vcpu = true;
> +	vcpu->arch.emulate_regs_need_sync_to_vcpu = false;
> +
> +	kvm_register_write(vcpu, VCPU_REGS_RAX, regs->rax);
> +	kvm_register_write(vcpu, VCPU_REGS_RBX, regs->rbx);
> +	kvm_register_write(vcpu, VCPU_REGS_RCX, regs->rcx);
> +	kvm_register_write(vcpu, VCPU_REGS_RDX, regs->rdx);
> +	kvm_register_write(vcpu, VCPU_REGS_RSI, regs->rsi);
> +	kvm_register_write(vcpu, VCPU_REGS_RDI, regs->rdi);
> +	kvm_register_write(vcpu, VCPU_REGS_RSP, regs->rsp);
> +	kvm_register_write(vcpu, VCPU_REGS_RBP, regs->rbp);
> +#ifdef CONFIG_X86_64
> +	kvm_register_write(vcpu, VCPU_REGS_R8, regs->r8);
> +	kvm_register_write(vcpu, VCPU_REGS_R9, regs->r9);
> +	kvm_register_write(vcpu, VCPU_REGS_R10, regs->r10);
> +	kvm_register_write(vcpu, VCPU_REGS_R11, regs->r11);
> +	kvm_register_write(vcpu, VCPU_REGS_R12, regs->r12);
> +	kvm_register_write(vcpu, VCPU_REGS_R13, regs->r13);
> +	kvm_register_write(vcpu, VCPU_REGS_R14, regs->r14);
> +	kvm_register_write(vcpu, VCPU_REGS_R15, regs->r15);
> +#endif
> +
> +	kvm_rip_write(vcpu, regs->rip);
> +	kvm_set_rflags(vcpu, regs->rflags);
> +
> +	kvm_make_request(KVM_REQ_EVENT, vcpu);
> +}
> +

kvm_arch_vcpu_ioctl_set_regs() returns an int (so that, for e.g., in ARM 
it can return an error to indicate that the function is not 
supported/implemented). Is there a reason this function shouldn't do the 
same (is it only ever going to be implemented for x86)?

>   void kvm_get_cs_db_l_bits(struct kvm_vcpu *vcpu, int *db, int *l)
>   {
>   	struct kvm_segment cs;
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 6bdd4b9f6611..68e4d756f5c9 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -767,6 +767,7 @@ int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu *vcpu,
>   
>   int kvm_arch_vcpu_ioctl_get_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs);
>   int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs);
> +void kvm_arch_vcpu_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs);
>   int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
>   				  struct kvm_sregs *sregs);
>   int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,


Patrick