Commit 2ea75be3 authored by David Matlack's avatar David Matlack Committed by Paolo Bonzini

kvm: don't take vcpu mutex for obviously invalid vcpu ioctls

vcpu ioctls can hang the calling thread if issued while a vcpu is running.
However, invalid ioctls can happen when userspace tries to probe the kind
of file descriptors (e.g. isatty() calls ioctl(TCGETS)); in that case,
we know the ioctl is going to be rejected as invalid anyway and we can
fail before trying to take the vcpu mutex.

This patch does not change functionality, it just makes invalid ioctls
fail faster.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarDavid Matlack <dmatlack@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 234b239b
...@@ -52,6 +52,7 @@ ...@@ -52,6 +52,7 @@
#include <asm/processor.h> #include <asm/processor.h>
#include <asm/io.h> #include <asm/io.h>
#include <asm/ioctl.h>
#include <asm/uaccess.h> #include <asm/uaccess.h>
#include <asm/pgtable.h> #include <asm/pgtable.h>
...@@ -2032,6 +2033,9 @@ static long kvm_vcpu_ioctl(struct file *filp, ...@@ -2032,6 +2033,9 @@ static long kvm_vcpu_ioctl(struct file *filp,
if (vcpu->kvm->mm != current->mm) if (vcpu->kvm->mm != current->mm)
return -EIO; return -EIO;
if (unlikely(_IOC_TYPE(ioctl) != KVMIO))
return -EINVAL;
#if defined(CONFIG_S390) || defined(CONFIG_PPC) || defined(CONFIG_MIPS) #if defined(CONFIG_S390) || defined(CONFIG_PPC) || defined(CONFIG_MIPS)
/* /*
* Special cases: vcpu ioctls that are asynchronous to vcpu execution, * Special cases: vcpu ioctls that are asynchronous to vcpu execution,
......
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