Commit 7a246504 authored by David Matlack's avatar David Matlack Committed by Greg Kroah-Hartman

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

commit 2ea75be3 upstream.

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.
Signed-off-by: default avatarDavid Matlack <dmatlack@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e58afde2
...@@ -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>
...@@ -1989,6 +1990,9 @@ static long kvm_vcpu_ioctl(struct file *filp, ...@@ -1989,6 +1990,9 @@ 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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