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| author | Masatake YAMATO <yamato@redhat.com> | 2018-01-20 04:04:22 +0900 |
|---|---|---|
| committer | Radim Krčmář <rkrcmar@redhat.com> | 2018-01-31 18:25:34 +0100 |
| commit | e46b469278a59781f9b25ff608af84892963821b (patch) | |
| tree | 0c36276e580a4f911c9207fab404ea3978511148 /virt | |
| parent | a340b3e229b24a56f1c7f5826b15a3af0f4b13e5 (diff) | |
| download | lwn-e46b469278a59781f9b25ff608af84892963821b.tar.gz lwn-e46b469278a59781f9b25ff608af84892963821b.zip | |
kvm: embed vcpu id to dentry of vcpu anon inode
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>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/kvm_main.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 8af42eab126d..8a937b7cde35 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2415,7 +2415,10 @@ static struct file_operations kvm_vcpu_fops = { */ static int create_vcpu_fd(struct kvm_vcpu *vcpu) { - return anon_inode_getfd("kvm-vcpu", &kvm_vcpu_fops, vcpu, O_RDWR | O_CLOEXEC); + char name[8 + 1 + ITOA_MAX_LEN + 1]; + + snprintf(name, sizeof(name), "kvm-vcpu:%d", vcpu->vcpu_id); + return anon_inode_getfd(name, &kvm_vcpu_fops, vcpu, O_RDWR | O_CLOEXEC); } static int kvm_create_vcpu_debugfs(struct kvm_vcpu *vcpu) |