path: root/drivers/s390/crypto/vfio_ap_ops.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Adjunct processor matrix VFIO device driver callbacks.
 *
 * Copyright IBM Corp. 2018
 *
 * Author(s): Tony Krowiak <akrowiak@linux.ibm.com>
 *	      Halil Pasic <pasic@linux.ibm.com>
 *	      Pierre Morel <pmorel@linux.ibm.com>
 */
#include <linux/string.h>
#include <linux/vfio.h>
#include <linux/device.h>
#include <linux/list.h>
#include <linux/ctype.h>
#include <linux/bitops.h>
#include <linux/kvm_host.h>
#include <linux/module.h>
#include <linux/uuid.h>
#include <asm/kvm.h>
#include <asm/zcrypt.h>

#include "vfio_ap_private.h"
#include "vfio_ap_debug.h"

#define VFIO_AP_MDEV_TYPE_HWVIRT "passthrough"
#define VFIO_AP_MDEV_NAME_HWVIRT "VFIO AP Passthrough Device"

static int vfio_ap_mdev_reset_queues(struct ap_matrix_mdev *matrix_mdev);
static struct vfio_ap_queue *vfio_ap_find_queue(int apqn);
static const struct vfio_device_ops vfio_ap_matrix_dev_ops;

static int match_apqn(struct device *dev, const void *data)
{
	struct vfio_ap_queue *q = dev_get_drvdata(dev);

	return (q->apqn == *(int *)(data)) ? 1 : 0;
}

/**
 * vfio_ap_get_queue - retrieve a queue with a specific APQN from a list
 * @matrix_mdev: the associated mediated matrix
 * @apqn: The queue APQN
 *
 * Retrieve a queue with a specific APQN from the list of the
 * devices of the vfio_ap_drv.
 * Verify that the APID and the APQI are set in the matrix.
 *
 * Return: the pointer to the associated vfio_ap_queue
 */
static struct vfio_ap_queue *vfio_ap_get_queue(
					struct ap_matrix_mdev *matrix_mdev,
					int apqn)
{
	struct vfio_ap_queue *q;

	if (!test_bit_inv(AP_QID_CARD(apqn), matrix_mdev->matrix.apm))
		return NULL;
	if (!test_bit_inv(AP_QID_QUEUE(apqn), matrix_mdev->matrix.aqm))
		return NULL;

	q = vfio_ap_find_queue(apqn);
	if (q)
		q->matrix_mdev = matrix_mdev;

	return q;
}

/**
 * vfio_ap_wait_for_irqclear - clears the IR bit or gives up after 5 tries
 * @apqn: The AP Queue number
 *
 * Checks the IRQ bit for the status of this APQN using ap_tapq.
 * Returns if the ap_tapq function succeeded and the bit is clear.
 * Returns if ap_tapq function failed with invalid, deconfigured or
 * checkstopped AP.
 * Otherwise retries up to 5 times after waiting 20ms.
 */
static void vfio_ap_wait_for_irqclear(int apqn)
{
	struct ap_queue_status status;
	int retry = 5;

	do {
		status = ap_tapq(apqn, NULL);
		switch (status.response_code) {
		case AP_RESPONSE_NORMAL:
		case AP_RESPONSE_RESET_IN_PROGRESS:
			if (!status.irq_enabled)
				return;
			fallthrough;
		case AP_RESPONSE_BUSY:
			msleep(20);
			break;
		case AP_RESPONSE_Q_NOT_AVAIL:
		case AP_RESPONSE_DECONFIGURED:
		case AP_RESPONSE_CHECKSTOPPED:
		default:
			WARN_ONCE(1, "%s: tapq rc %02x: %04x\n", __func__,
				  status.response_code, apqn);
			return;
		}
	} while (--retry);

	WARN_ONCE(1, "%s: tapq rc %02x: %04x could not clear IR bit\n",
		  __func__, status.response_code, apqn);
}

/**
 * vfio_ap_free_aqic_resources - free vfio_ap_queue resources
 * @q: The vfio_ap_queue
 *
 * Unregisters the ISC in the GIB when the saved ISC not invalid.
 * Unpins the guest's page holding the NIB when it exists.
 * Resets the saved_pfn and saved_isc to invalid values.
 */
static void vfio_ap_free_aqic_resources(struct vfio_ap_queue *q)
{
	if (!q)
		return;
	if (q->saved_isc != VFIO_AP_ISC_INVALID &&
	    !WARN_ON(!(q->matrix_mdev && q->matrix_mdev->kvm))) {
		kvm_s390_gisc_unregister(q->matrix_mdev->kvm, q->saved_isc);
		q->saved_isc = VFIO_AP_ISC_INVALID;
	}
	if (q->saved_pfn && !WARN_ON(!q->matrix_mdev)) {
		vfio_unpin_pages(mdev_dev(q->matrix_mdev->mdev),
				 &q->saved_pfn, 1);
		q->saved_pfn = 0;
	}
}

/**
 * vfio_ap_irq_disable - disables and clears an ap_queue interrupt
 * @q: The vfio_ap_queue
 *
 * Uses ap_aqic to disable the interruption and in case of success, reset
 * in progress or IRQ disable command already proceeded: calls
 * vfio_ap_wait_for_irqclear() to check for the IRQ bit to be clear
 * and calls vfio_ap_free_aqic_resources() to free the resources associated
 * with the AP interrupt handling.
 *
 * In the case the AP is busy, or a reset is in progress,
 * retries after 20ms, up to 5 times.
 *
 * Returns if ap_aqic function failed with invalid, deconfigured or
 * checkstopped AP.
 *
 * Return: &struct ap_queue_status
 */
static struct ap_queue_status vfio_ap_irq_disable(struct vfio_ap_queue *q)
{
	struct ap_qirq_ctrl aqic_gisa = {};
	struct ap_queue_status status;
	int retries = 5;

	do {
		status = ap_aqic(q->apqn, aqic_gisa, NULL);
		switch (status.response_code) {
		case AP_RESPONSE_OTHERWISE_CHANGED:
		case AP_RESPONSE_NORMAL:
			vfio_ap_wait_for_irqclear(q->apqn);
			goto end_free;
		case AP_RESPONSE_RESET_IN_PROGRESS:
		case AP_RESPONSE_BUSY:
			msleep(20);
			break;
		case AP_RESPONSE_Q_NOT_AVAIL:
		case AP_RESPONSE_DECONFIGURED:
		case AP_RESPONSE_CHECKSTOPPED:
		case AP_RESPONSE_INVALID_ADDRESS:
		default:
			/* All cases in default means AP not operational */
			WARN_ONCE(1, "%s: ap_aqic status %d\n", __func__,
				  status.response_code);
			goto end_free;
		}
	} while (retries--);

	WARN_ONCE(1, "%s: ap_aqic status %d\n", __func__,
		  status.response_code);
end_free:
	vfio_ap_free_aqic_resources(q);
	q->matrix_mdev = NULL;
	return status;
}

/**
 * vfio_ap_validate_nib - validate a notification indicator byte (nib) address.
 *
 * @vcpu: the object representing the vcpu executing the PQAP(AQIC) instruction.
 * @nib: the location for storing the nib address.
 * @g_pfn: the location for storing the page frame number of the page containing
 *	   the nib.
 *
 * When the PQAP(AQIC) instruction is executed, general register 2 contains the
 * address of the notification indicator byte (nib) used for IRQ notification.
 * This function parses the nib from gr2 and calculates the page frame
 * number for the guest of the page containing the nib. The values are
 * stored in @nib and @g_pfn respectively.
 *
 * The g_pfn of the nib is then validated to ensure the nib address is valid.
 *
 * Return: returns zero if the nib address is a valid; otherwise, returns
 *	   -EINVAL.
 */
static int vfio_ap_validate_nib(struct kvm_vcpu *vcpu, unsigned long *nib,
				unsigned long *g_pfn)
{
	*nib = vcpu->run->s.regs.gprs[2];
	*g_pfn = *nib >> PAGE_SHIFT;

	if (kvm_is_error_hva(gfn_to_hva(vcpu->kvm, *g_pfn)))
		return -EINVAL;

	return 0;
}

/**
 * vfio_ap_irq_enable - Enable Interruption for a APQN
 *
 * @q:	 the vfio_ap_queue holding AQIC parameters
 * @isc: the guest ISC to register with the GIB interface
 * @vcpu: the vcpu object containing the registers specifying the parameters
 *	  passed to the PQAP(AQIC) instruction.
 *
 * Pin the NIB saved in *q
 * Register the guest ISC to GIB int