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SubjectRe: [PATCH] kvm: don't take vcpu mutex for obviously invalid vcpu ioctls
Il 20/09/2014 01:03, David Matlack ha scritto:
> vcpu ioctls can hang the calling thread if issued while a vcpu is
> running. If we know ioctl is going to be rejected as invalid anyway,
> we can fail before trying to take the vcpu mutex.
>
> This patch does not change functionality, it just makes invalid ioctls
> fail faster.
>
> Signed-off-by: David Matlack <dmatlack@google.com>
> ---
> virt/kvm/kvm_main.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 96ec622..f9234e5 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -52,6 +52,7 @@
>
> #include <asm/processor.h>
> #include <asm/io.h>
> +#include <asm/ioctl.h>
> #include <asm/uaccess.h>
> #include <asm/pgtable.h>
>
> @@ -1975,6 +1976,9 @@ static long kvm_vcpu_ioctl(struct file *filp,
> if (vcpu->kvm->mm != current->mm)
> return -EIO;
>
> + if (unlikely(_IOC_TYPE(ioctl) != KVMIO))
> + return -EINVAL;
> +
> #if defined(CONFIG_S390) || defined(CONFIG_PPC) || defined(CONFIG_MIPS)
> /*
> * Special cases: vcpu ioctls that are asynchronous to vcpu execution,
>

Thanks, applying this patch.

Paolo


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