Dont leak debug flugs in ioctl_get_regs()?

Dont leak debug flugs in ioctl_get_regs()?

[Jun Koi]

Hi,

In kvm_vcpu_ioctl_get_regs() function (kvm_main.c), we have a comment
like this: "Dont leak debug flags in case they were set for guest
debugging".

What is the reasons that make us filter out TF and RF bit in EFLAGS like that?

Thanks,
Jun

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Re: Dont leak debug flugs in ioctl_get_regs()?

[Avi Kivity]

Jun Koi wrote:
> Hi,
>
> In kvm_vcpu_ioctl_get_regs() function (kvm_main.c), we have a comment
> like this: "Dont leak debug flags in case they were set for guest
> debugging".
>
> What is the reasons that make us filter out TF and RF bit in EFLAGS like that?
>   

VT and SVM don't virtualize the debug flags.  So when we debug the 
guest, we modify the guest's TF and RF, not some hardware-provided 
shadow register.  So, when we look at the guest's eflags, we need to 
consider that some of the bits are owned by the host, not the guest.

-- 
error compiling committee.c: too many arguments to function


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