Re: [PATCH resend] kvm: embed vcpu id to dentry of vcpu anon inode

["Radim Krčmář" <rkrcmar@redhat.com>]

2018-01-20 04:04+0900, Masatake YAMATO:
> All d-entries for vcpu have the same, "anon_inode:kvm-vcpu". That means
> it is impossible to know the mapping between fds for vcpu and vcpu
> from userland.
> 
>     # LC_ALL=C ls -l /proc/617/fd | grep vcpu
>     lrwx------. 1 qemu qemu 64 Jan  7 16:50 18 -> anon_inode:kvm-vcpu
>     lrwx------. 1 qemu qemu 64 Jan  7 16:50 19 -> anon_inode:kvm-vcpu
> 
> It is also impossible to know the mapping between vma for kvm_run
> structure and vcpu from userland.
> 
>     # LC_ALL=C grep vcpu /proc/617/maps
>     7f9d842d0000-7f9d842d3000 rw-s 00000000 00:0d 20393                      anon_inode:kvm-vcpu
>     7f9d842d3000-7f9d842d6000 rw-s 00000000 00:0d 20393                      anon_inode:kvm-vcpu
> 
> This change adds vcpu id to d-entries for vcpu. With this change
> you can get the following output:
> 
>     # LC_ALL=C ls -l /proc/617/fd | grep vcpu
>     lrwx------. 1 qemu qemu 64 Jan  7 16:50 18 -> anon_inode:kvm-vcpu:0
>     lrwx------. 1 qemu qemu 64 Jan  7 16:50 19 -> anon_inode:kvm-vcpu:1
> 
>     # LC_ALL=C grep vcpu /proc/617/maps
>     7f9d842d0000-7f9d842d3000 rw-s 00000000 00:0d 20393                      anon_inode:kvm-vcpu:0
>     7f9d842d3000-7f9d842d6000 rw-s 00000000 00:0d 20393                      anon_inode:kvm-vcpu:1
> 
> With the mappings known from the output, a tool like strace can report more details
> of qemu-kvm process activities. Here is the strace output of my local prototype:
> 
>     # ./strace -KK -f -p 617 2>&1 | grep 'KVM_RUN\| K'
>     ...
>     [pid   664] ioctl(18, KVM_RUN, 0)       = 0 (KVM_EXIT_MMIO)
>      K ready_for_interrupt_injection=1, if_flag=0, flags=0, cr8=0000000000000000, apic_base=0x000000fee00d00
>      K phys_addr=0, len=1634035803, [33, 0, 0, 0, 0, 0, 0, 0], is_write=112
>     [pid   664] ioctl(18, KVM_RUN, 0)       = 0 (KVM_EXIT_MMIO)
>      K ready_for_interrupt_injection=1, if_flag=1, flags=0, cr8=0000000000000000, apic_base=0x000000fee00d00
>      K phys_addr=0, len=1634035803, [33, 0, 0, 0, 0, 0, 0, 0], is_write=112
>     ...
> 
> Signed-off-by: Masatake YAMATO <yamato@redhat.com>
> ---

Queued, thanks.