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, 244 insertions, 0 deletions

diff --git a/drivers/media/firewire/firedtv-dvb.c b/drivers/media/firewire/firedtv-dvb.c
new file mode 100644
index 000000000..3b7e2f1ec
--- /dev/null
+++ b/drivers/media/firewire/firedtv-dvb.c
@@ -0,0 +1,244 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * FireDTV driver (formerly known as FireSAT)
+ *
+ * Copyright (C) 2004 Andreas Monitzer <andy@monitzer.com>
+ * Copyright (C) 2008 Henrik Kurelid <henrik@kurelid.se>
+ */
+
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/types.h>
+
+#include <media/dmxdev.h>
+#include <media/dvb_demux.h>
+#include <media/dvbdev.h>
+#include <media/dvb_frontend.h>
+
+#include "firedtv.h"
+
+static int alloc_channel(struct firedtv *fdtv)
+{
+	int i;
+
+	for (i = 0; i < 16; i++)
+		if (!__test_and_set_bit(i, &fdtv->channel_active))
+			break;
+	return i;
+}
+
+static void collect_channels(struct firedtv *fdtv, int *pidc, u16 pid[])
+{
+	int i, n;
+
+	for (i = 0, n = 0; i < 16; i++)
+		if (test_bit(i, &fdtv->channel_active))
+			pid[n++] = fdtv->channel_pid[i];
+	*pidc = n;
+}
+
+static inline void dealloc_channel(struct firedtv *fdtv, int i)
+{
+	__clear_bit(i, &fdtv->channel_active);
+}
+
+int fdtv_start_feed(struct dvb_demux_feed *dvbdmxfeed)
+{
+	struct firedtv *fdtv = dvbdmxfeed->demux->priv;
+	int pidc, c, ret;
+	u16 pids[16];
+
+	switch (dvbdmxfeed->type) {
+	case DMX_TYPE_TS:
+	case DMX_TYPE_SEC:
+		break;
+	default:
+		dev_err(fdtv->device, "can't start dmx feed: invalid type %u\n",
+			dvbdmxfeed->type);
+		return -EINVAL;
+	}
+
+	if (mutex_lock_interruptible(&fdtv->demux_mutex))
+		return -EINTR;
+
+	if (dvbdmxfeed->type == DMX_TYPE_TS) {
+		switch (dvbdmxfeed->pes_type) {
+		case DMX_PES_VIDEO:
+		case DMX_PES_AUDIO:
+		case DMX_PES_TELETEXT:
+		case DMX_PES_PCR:
+		case DMX_PES_OTHER:
+			c = alloc_channel(fdtv);
+			break;
+		default:
+			dev_err(fdtv->device,
+				"can't start dmx feed: invalid pes type %u\n",
+				dvbdmxfeed->pes_type);
+			ret = -EINVAL;
+			goto out;
+		}
+	} else {
+		c = alloc_channel(fdtv);
+	}
+
+	if (c > 15) {
+		dev_err(fdtv->device, "can't start dmx feed: busy\n");
+		ret = -EBUSY;
+		goto out;
+	}
+
+	dvbdmxfeed->priv = (typeof(dvbdmxfeed->priv))(unsigned long)c;
+	fdtv->channel_pid[c] = dvbdmxfeed->pid;
+	collect_channels(fdtv, &pidc, pids);
+
+	if (dvbdmxfeed->pid == 8192) {
+		ret = avc_tuner_get_ts(fdtv);
+		if (ret) {
+			dealloc_channel(fdtv, c);
+			dev_err(fdtv->device, "can't get TS\n");
+			goto out;
+		}
+	} else {
+		ret = avc_tuner_set_pids(fdtv, pidc, pids);
+		if (ret) {
+			dealloc_channel(fdtv, c);
+			dev_err(fdtv->device, "can't set PIDs\n");
+			goto out;
+		}
+	}
+out:
+	mutex_unlock(&fdtv->demux_mutex);
+
+	return ret;
+}
+
+int fdtv_stop_feed(struct dvb_demux_feed *dvbdmxfeed)
+{
+	struct dvb_demux *demux = dvbdmxfeed->demux;
+	struct firedtv *fdtv = demux->priv;
+	int pidc, c, ret;
+	u16 pids[16];
+
+	if (dvbdmxfeed->type == DMX_TYPE_TS &&
+	    !((dvbdmxfeed->ts_type & TS_PACKET) &&
+	      (demux->dmx.frontend->source != DMX_MEMORY_FE))) {
+
+		if (dvbdmxfeed->ts_type & TS_DECODER) {
+			if (dvbdmxfeed->pes_type >= DMX_PES_OTHER ||
+			    !demux->pesfilter[dvbdmxfeed->pes_type])
+				return -EINVAL;
+
+			demux->pids[dvbdmxfeed->pes_type] |= 0x8000;
+			demux->pesfilter[dvbdmxfeed->pes_type] = NULL;
+		}
+
+		if (!(dvbdmxfeed->ts_type & TS_DECODER &&
+		      dvbdmxfeed->pes_type < DMX_PES_OTHER))
+			return 0;
+	}
+
+	if (mutex_lock_interruptible(&fdtv->demux_mutex))
+		return -EINTR;
+
+	c = (unsigned long)dvbdmxfeed->priv;
+	dealloc_channel(fdtv, c);
+	collect_channels(fdtv, &pidc, pids);
+
+	ret = avc_tuner_set_pids(fdtv, pidc, pids);
+
+	mutex_unlock(&fdtv->demux_mutex);
+
+	return ret;
+}
+
+DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nr);
+
+int fdtv_dvb_register(struct firedtv *fdtv, const char *name)
+{
+	int err;
+
+	err = dvb_register_adapter(&fdtv->adapter, name,
+				   THIS_MODULE, fdtv->device, adapter_nr);
+	if (err < 0)
+		goto fail_log;
+
+	/*DMX_TS_FILTERING | DMX_SECTION_FILTERING*/
+	fdtv->demux.dmx.capabilities = 0;
+
+	fdtv->demux.priv	= fdtv;
+	fdtv->demux.filternum	= 16;
+	fdtv->demux.feednum	= 16;
+	fdtv->demux.start_feed	= fdtv_start_feed;
+	fdtv->demux.stop_feed	= fdtv_stop_feed;
+	fdtv->demux.write_to_decoder = NULL;
+
+	err = dvb_dmx_init(&fdtv->demux);
+	if (err)
+		goto fail_unreg_adapter;
+
+	fdtv->dmxdev.filternum    = 16;
+	fdtv->dmxdev.demux        = &fdtv->demux.dmx;
+	fdtv->dmxdev.capabilities = 0;
+
+	err = dvb_dmxdev_init(&fdtv->dmxdev, &fdtv->adapter);
+	if (err)
+		goto fail_dmx_release;
+
+	fdtv->frontend.source = DMX_FRONTEND_0;
+
+	err = fdtv->demux.dmx.add_frontend(&fdtv->demux.dmx, &fdtv->frontend);
+	if (err)
+		goto fail_dmxdev_release;
+
+	err = fdtv->demux.dmx.connect_frontend(&fdtv->demux.dmx,
+					       &fdtv->frontend);
+	if (err)
+		goto fail_rem_frontend;
+
+	err = dvb_net_init(&fdtv->adapter, &fdtv->dvbnet, &fdtv->demux.dmx);
+	if (err)
+		goto fail_disconnect_frontend;
+
+	fdtv_frontend_init(fdtv, name);
+	err = dvb_register_frontend(&fdtv->adapter, &fdtv->fe);
+	if (err)
+		goto fail_net_release;
+
+	err = fdtv_ca_register(fdtv);
+	if (err)
+		dev_info(fdtv->device,
+			 "Conditional Access Module not enabled\n");
+	return 0;
+
+fail_net_release:
+	dvb_net_release(&fdtv->dvbnet);
+fail_disconnect_frontend:
+	fdtv->demux.dmx.close(&fdtv->demux.dmx);
+fail_rem_frontend:
+	fdtv->demux.dmx.remove_frontend(&fdtv->demux.dmx, &fdtv->frontend);
+fail_dmxdev_release:
+	dvb_dmxdev_release(&fdtv->dmxdev);
+fail_dmx_release:
+	dvb_dmx_release(&fdtv->demux);
+fail_unreg_adapter:
+	dvb_unregister_adapter(&fdtv->adapter);
+fail_log:
+	dev_err(fdtv->device, "DVB initialization failed\n");
+	return err;
+}
+
+void fdtv_dvb_unregister(struct firedtv *fdtv)
+{
+	fdtv_ca_release(fdtv);
+	dvb_unregister_frontend(&fdtv->fe);
+	dvb_net_release(&fdtv->dvbnet);
+	fdtv->demux.dmx.close(&fdtv->demux.dmx);
+	fdtv->demux.dmx.remove_frontend(&fdtv->demux.dmx, &fdtv->frontend);
+	dvb_dmxdev_release(&fdtv->dmxdev);
+	dvb_dmx_release(&fdtv->demux);
+	dvb_unregister_adapter(&fdtv->adapter);
+}