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KVM: Allow kernel to select size of mmap() buffer

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This allows us to store offsets in the kernel/user kvm_run area, and be
sure that userspace has them mapped.  As offsets can be outside the
kvm_run struct, userspace has no way of knowing how much to mmap.

Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Avi Kivity 2007-03-07 13:05:38 +02:00
parent 1961d276c8
commit 07c45a366d
2 changed files with 11 additions and 1 deletions
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8
drivers/kvm/kvm_main.c
View File

@ -2436,7 +2436,7 @@ static long kvm_dev_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
void __user *argp = (void __user *)arg;
int r = -EINVAL;
long r = -EINVAL;
switch (ioctl) {
case KVM_GET_API_VERSION:
@ -2478,6 +2478,12 @@ static long kvm_dev_ioctl(struct file *filp,
*/
r = 0;
break;
case KVM_GET_VCPU_MMAP_SIZE:
r = -EINVAL;
if (arg)
goto out;
r = PAGE_SIZE;
break;
default:
;
}

4
include/linux/kvm.h
View File

@ -253,6 +253,10 @@ struct kvm_signal_mask {
* return is 1 (yes) or 0 (no, sorry).
*/
#define KVM_CHECK_EXTENSION _IO(KVMIO, 0x03)
/*
* Get size for mmap(vcpu_fd)
*/
#define KVM_GET_VCPU_MMAP_SIZE _IO(KVMIO, 0x04) /* in bytes */
/*
* ioctls for VM fds