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Commit 07c45a36 authored by Avi Kivity's avatar Avi Kivity
Browse files

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



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: default avatarAvi Kivity <avi@qumranet.com>
parent 1961d276

drivers/kvm/kvm_main.c

+7 −1
Original line number Diff line number Diff line
@@ -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:

		;

	}

include/linux/kvm.h

+4 −0
Original line number Diff line number Diff line
@@ -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