KVM: s390: add lowcore access functions

/*

 * access guest memory

 *

 * Copyright IBM Corp. 2008, 2009

 * Copyright IBM Corp. 2008, 2014

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License (version 2 only)

#include <linux/compiler.h>

#include <linux/kvm_host.h>

#include <asm/uaccess.h>

#include <linux/uaccess.h>

#include <linux/ptrace.h>

#include "kvm-s390.h"

/* Convert real to absolute address by applying the prefix of the CPU */

#define copy_from_guest_absolute(vcpu, to, from, size) \

	__copy_guest(vcpu, (unsigned long)to, from, size, 0, 0)

/*

 * put_guest_lc, read_guest_lc and write_guest_lc are guest access functions

 * which shall only be used to access the lowcore of a vcpu.

 * These functions should be used for e.g. interrupt handlers where no

 * guest memory access protection facilities, like key or low address

 * protection, are applicable.

 * At a later point guest vcpu lowcore access should happen via pinned

 * prefix pages, so that these pages can be accessed directly via the

 * kernel mapping. All of these *_lc functions can be removed then.

 */

/**

 * put_guest_lc - write a simple variable to a guest vcpu's lowcore

 * @vcpu: virtual cpu

 * @x: value to copy to guest

 * @gra: vcpu's destination guest real address

 *

 * Copies a simple value from kernel space to a guest vcpu's lowcore.

 * The size of the variable may be 1, 2, 4 or 8 bytes. The destination

 * must be located in the vcpu's lowcore. Otherwise the result is undefined.

 *

 * Returns zero on success or -EFAULT on error.

 *

 * Note: an error indicates that either the kernel is out of memory or

 *	 the guest memory mapping is broken. In any case the best solution

 *	 would be to terminate the guest.

 *	 It is wrong to inject a guest exception.

 */

#define put_guest_lc(vcpu, x, gra)				\

({								\

	struct kvm_vcpu *__vcpu = (vcpu);			\

	__typeof__(*(gra)) __x = (x);				\

	unsigned long __gpa;					\

								\

	__gpa = (unsigned long)(gra);				\

	__gpa += __vcpu->arch.sie_block->prefix;		\

	kvm_write_guest(__vcpu->kvm, __gpa, &__x, sizeof(__x));	\

})

/**

 * write_guest_lc - copy data from kernel space to guest vcpu's lowcore

 * @vcpu: virtual cpu

 * @gra: vcpu's source guest real address

 * @data: source address in kernel space

 * @len: number of bytes to copy

 *

 * Copy data from kernel space to guest vcpu's lowcore. The entire range must

 * be located within the vcpu's lowcore, otherwise the result is undefined.

 *

 * Returns zero on success or -EFAULT on error.

 *

 * Note: an error indicates that either the kernel is out of memory or

 *	 the guest memory mapping is broken. In any case the best solution

 *	 would be to terminate the guest.

 *	 It is wrong to inject a guest exception.

 */

static inline __must_check

int write_guest_lc(struct kvm_vcpu *vcpu, unsigned long gra, void *data,

		   unsigned long len)

{

	unsigned long gpa = gra + vcpu->arch.sie_block->prefix;

	return kvm_write_guest(vcpu->kvm, gpa, data, len);

}

/**

 * read_guest_lc - copy data from guest vcpu's lowcore to kernel space

 * @vcpu: virtual cpu

 * @gra: vcpu's source guest real address

 * @data: destination address in kernel space

 * @len: number of bytes to copy

 *

 * Copy data from guest vcpu's lowcore to kernel space. The entire range must

 * be located within the vcpu's lowcore, otherwise the result is undefined.

 *

 * Returns zero on success or -EFAULT on error.

 *

 * Note: an error indicates that either the kernel is out of memory or

 *	 the guest memory mapping is broken. In any case the best solution

 *	 would be to terminate the guest.

 *	 It is wrong to inject a guest exception.

 */

static inline __must_check

int read_guest_lc(struct kvm_vcpu *vcpu, unsigned long gra, void *data,

		  unsigned long len)

{

	unsigned long gpa = gra + vcpu->arch.sie_block->prefix;

	return kvm_read_guest(vcpu->kvm, gpa, data, len);

}

#endif /* __KVM_S390_GACCESS_H */