KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

Manually perform cache maintenance on the source VM during intra-host
migration to ensure no stale data is left in CPU caches after the VM is
destroyed.  Because the source VM is "converted" to a non-SEV VM, KVM's
memory reclaim flows won't trigger cache maintenance, e.g. when all guest
memory is reclaimed in response to detaching from the mmu_notifier.

Note, relying on the destination VM to do cache maintenance isn't an option
as KVM doesn't require identical guest memory configurations, i.e. the
source VM may have access to memory that the destination VM does not.
Enforcing equivalent memory configurations is infeasible, as it would
require a *deep* comparison of memslots, e.g. to verify that not only are
the memslot identical, but what the memslots point at is also identical.

Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration")
Cc: stable@vger.kernel.org
Reported-by: Stefan Teodorescu <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 250 insertions, 0 deletions

diff --git a/drivers/fpga/dfl-afu-error.c b/drivers/fpga/dfl-afu-error.c
new file mode 100644
index 000000000..0f392d1f6
--- /dev/null
+++ b/drivers/fpga/dfl-afu-error.c
@@ -0,0 +1,250 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for FPGA Accelerated Function Unit (AFU) Error Reporting
+ *
+ * Copyright 2019 Intel Corporation, Inc.
+ *
+ * Authors:
+ *   Wu Hao <hao.wu@linux.intel.com>
+ *   Xiao Guangrong <guangrong.xiao@linux.intel.com>
+ *   Joseph Grecco <joe.grecco@intel.com>
+ *   Enno Luebbers <enno.luebbers@intel.com>
+ *   Tim Whisonant <tim.whisonant@intel.com>
+ *   Ananda Ravuri <ananda.ravuri@intel.com>
+ *   Mitchel Henry <henry.mitchel@intel.com>
+ */
+
+#include <linux/fpga-dfl.h>
+#include <linux/uaccess.h>
+
+#include "dfl-afu.h"
+
+#define PORT_ERROR_MASK		0x8
+#define PORT_ERROR		0x10
+#define PORT_FIRST_ERROR	0x18
+#define PORT_MALFORMED_REQ0	0x20
+#define PORT_MALFORMED_REQ1	0x28
+
+#define ERROR_MASK		GENMASK_ULL(63, 0)
+
+/* mask or unmask port errors by the error mask register. */
+static void __afu_port_err_mask(struct dfl_feature_dev_data *fdata, bool mask)
+{
+	void __iomem *base;
+
+	base = dfl_get_feature_ioaddr_by_id(fdata, PORT_FEATURE_ID_ERROR);
+
+	writeq(mask ? ERROR_MASK : 0, base + PORT_ERROR_MASK);
+}
+
+static void afu_port_err_mask(struct device *dev, bool mask)
+{
+	struct dfl_feature_dev_data *fdata = to_dfl_feature_dev_data(dev);
+
+	mutex_lock(&fdata->lock);
+	__afu_port_err_mask(fdata, mask);
+	mutex_unlock(&fdata->lock);
+}
+
+/* clear port errors. */
+static int afu_port_err_clear(struct device *dev, u64 err)
+{
+	struct dfl_feature_dev_data *fdata = to_dfl_feature_dev_data(dev);
+	void __iomem *base_err, *base_hdr;
+	int enable_ret = 0, ret = -EBUSY;
+	u64 v;
+
+	base_err = dfl_get_feature_ioaddr_by_id(fdata, PORT_FEATURE_ID_ERROR);
+	base_hdr = dfl_get_feature_ioaddr_by_id(fdata, PORT_FEATURE_ID_HEADER);
+
+	mutex_lock(&fdata->lock);
+
+	/*
+	 * clear Port Errors
+	 *
+	 * - Check for AP6 State
+	 * - Halt Port by keeping Port in reset
+	 * - Set PORT Error mask to all 1 to mask errors
+	 * - Clear all errors
+	 * - Set Port mask to all 0 to enable errors
+	 * - All errors start capturing new errors
+	 * - Enable Port by pulling the port out of reset
+	 */
+
+	/* if device is still in AP6 power state, can not clear any error. */
+	v = readq(base_hdr + PORT_HDR_STS);
+	if (FIELD_GET(PORT_STS_PWR_STATE, v) == PORT_STS_PWR_STATE_AP6) {
+		dev_err(dev, "Could not clear errors, device in AP6 state.\n");
+		goto done;
+	}
+
+	/* Halt Port by keeping Port in reset */
+	ret = __afu_port_disable(fdata);
+	if (ret)
+		goto done;
+
+	/* Mask all errors */
+	__afu_port_err_mask(fdata, true);
+
+	/* Clear errors if err input matches with current port errors.*/
+	v = readq(base_err + PORT_ERROR);
+
+	if (v == err) {
+		writeq(v, base_err + PORT_ERROR);
+
+		v = readq(base_err + PORT_FIRST_ERROR);
+		writeq(v, base_err + PORT_FIRST_ERROR);
+	} else {
+		dev_warn(dev, "%s: received 0x%llx, expected 0x%llx\n",
+			 __func__, v, err);
+		ret = -EINVAL;
+	}
+
+	/* Clear mask */
+	__afu_port_err_mask(fdata, false);
+
+	/* Enable the Port by clearing the reset */
+	enable_ret = __afu_port_enable(fdata);
+
+done:
+	mutex_unlock(&fdata->lock);
+	return enable_ret ? enable_ret : ret;
+}
+
+static ssize_t errors_show(struct device *dev, struct device_attribute *attr,
+			   char *buf)
+{
+	struct dfl_feature_dev_data *fdata = to_dfl_feature_dev_data(dev);
+	void __iomem *base;
+	u64 error;
+
+	base = dfl_get_feature_ioaddr_by_id(fdata, PORT_FEATURE_ID_ERROR);
+
+	mutex_lock(&fdata->lock);
+	error = readq(base + PORT_ERROR);
+	mutex_unlock(&fdata->lock);
+
+	return sprintf(buf, "0x%llx\n", (unsigned long long)error);
+}
+
+static ssize_t errors_store(struct device *dev, struct device_attribute *attr,
+			    const char *buff, size_t count)
+{
+	u64 value;
+	int ret;
+
+	if (kstrtou64(buff, 0, &value))
+		return -EINVAL;
+
+	ret = afu_port_err_clear(dev, value);
+
+	return ret ? ret : count;
+}
+static DEVICE_ATTR_RW(errors);
+
+static ssize_t first_error_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct dfl_feature_dev_data *fdata = to_dfl_feature_dev_data(dev);
+	void __iomem *base;
+	u64 error;
+
+	base = dfl_get_feature_ioaddr_by_id(fdata, PORT_FEATURE_ID_ERROR);
+
+	mutex_lock(&fdata->lock);
+	error = readq(base + PORT_FIRST_ERROR);
+	mutex_unlock(&fdata->lock);
+
+	return sprintf(buf, "0x%llx\n", (unsigned long long)error);
+}
+static DEVICE_ATTR_RO(first_error);
+
+static ssize_t first_malformed_req_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct dfl_feature_dev_data *fdata = to_dfl_feature_dev_data(dev);
+	void __iomem *base;
+	u64 req0, req1;
+
+	base = dfl_get_feature_ioaddr_by_id(fdata, PORT_FEATURE_ID_ERROR);
+
+	mutex_lock(&fdata->lock);
+	req0 = readq(base + PORT_MALFORMED_REQ0);
+	req1 = readq(base + PORT_MALFORMED_REQ1);
+	mutex_unlock(&fdata->lock);
+
+	return sprintf(buf, "0x%016llx%016llx\n",
+		       (unsigned long long)req1, (unsigned long long)req0);
+}
+static DEVICE_ATTR_RO(first_malformed_req);
+
+static struct attribute *port_err_attrs[] = {
+	&dev_attr_errors.attr,
+	&dev_attr_first_error.attr,
+	&dev_attr_first_malformed_req.attr,
+	NULL,
+};
+
+static umode_t port_err_attrs_visible(struct kobject *kobj,
+				      struct attribute *attr, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct dfl_feature_dev_data *fdata;
+
+	fdata = to_dfl_feature_dev_data(dev);
+	/*
+	 * sysfs entries are visible only if related private feature is
+	 * enumerated.
+	 */
+	if (!dfl_get_feature_by_id(fdata, PORT_FEATURE_ID_ERROR))
+		return 0;
+
+	return attr->mode;
+}
+
+const struct attribute_group port_err_group = {
+	.name       = "errors",
+	.attrs      = port_err_attrs,
+	.is_visible = port_err_attrs_visible,
+};
+
+static int port_err_init(struct platform_device *pdev,
+			 struct dfl_feature *feature)
+{
+	afu_port_err_mask(&pdev->dev, false);
+
+	return 0;
+}
+
+static void port_err_uinit(struct platform_device *pdev,
+			   struct dfl_feature *feature)
+{
+	afu_port_err_mask(&pdev->dev, true);
+}
+
+static long
+port_err_ioctl(struct platform_device *pdev, struct dfl_feature *feature,
+	       unsigned int cmd, unsigned long arg)
+{
+	switch (cmd) {
+	case DFL_FPGA_PORT_ERR_GET_IRQ_NUM:
+		return dfl_feature_ioctl_get_num_irqs(pdev, feature, arg);
+	case DFL_FPGA_PORT_ERR_SET_IRQ:
+		return dfl_feature_ioctl_set_irq(pdev, feature, arg);
+	default:
+		dev_dbg(&pdev->dev, "%x cmd not handled", cmd);
+		return -ENODEV;
+	}
+}
+
+const struct dfl_feature_id port_err_id_table[] = {
+	{.id = PORT_FEATURE_ID_ERROR,},
+	{0,}
+};
+
+const struct dfl_feature_ops port_err_ops = {
+	.init = port_err_init,
+	.uinit = port_err_uinit,
+	.ioctl = port_err_ioctl,
+};