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, 265 insertions, 0 deletions

diff --git a/arch/mips/sni/setup.c b/arch/mips/sni/setup.c
new file mode 100644
index 000000000..fc7da1228
--- /dev/null
+++ b/arch/mips/sni/setup.c
@@ -0,0 +1,265 @@
+/*
+ * Setup pointers to hardware-dependent routines.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1996, 97, 98, 2000, 03, 04, 06 Ralf Baechle (ralf@linux-mips.org)
+ * Copyright (C) 2006,2007 Thomas Bogendoerfer (tsbogend@alpha.franken.de)
+ */
+#include <linux/eisa.h>
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/console.h>
+#include <linux/screen_info.h>
+#include <linux/string.h>
+
+#ifdef CONFIG_FW_ARC
+#include <asm/fw/arc/types.h>
+#include <asm/sgialib.h>
+#endif
+
+#ifdef CONFIG_FW_SNIPROM
+#include <asm/mipsprom.h>
+#endif
+
+#include <asm/bootinfo.h>
+#include <asm/cpu.h>
+#include <asm/io.h>
+#include <asm/reboot.h>
+#include <asm/sni.h>
+
+unsigned int sni_brd_type;
+EXPORT_SYMBOL(sni_brd_type);
+
+extern void sni_machine_restart(char *command);
+extern void sni_machine_power_off(void);
+
+static void __init sni_display_setup(void)
+{
+#if defined(CONFIG_VGA_CONSOLE) && defined(CONFIG_FW_ARC)
+	static struct screen_info si;
+	DISPLAY_STATUS *di;
+
+	di = ArcGetDisplayStatus(1);
+
+	if (di) {
+		si.orig_x		= di->CursorXPosition;
+		si.orig_y		= di->CursorYPosition;
+		si.orig_video_cols	= di->CursorMaxXPosition;
+		si.orig_video_lines	= di->CursorMaxYPosition;
+		si.orig_video_isVGA	= VIDEO_TYPE_VGAC;
+		si.orig_video_points	= 16;
+
+		vgacon_register_screen(&si);
+	}
+#endif
+}
+
+static void __init sni_console_setup(void)
+{
+#ifndef CONFIG_FW_ARC
+	char *ctype;
+	char *cdev;
+	char *baud;
+	int port;
+	static char options[8] __initdata;
+
+	cdev = prom_getenv("console_dev");
+	if (strncmp(cdev, "tty", 3) == 0) {
+		ctype = prom_getenv("console");
+		switch (*ctype) {
+		default:
+		case 'l':
+			port = 0;
+			baud = prom_getenv("lbaud");
+			break;
+		case 'r':
+			port = 1;
+			baud = prom_getenv("rbaud");
+			break;
+		}
+		if (baud)
+			strscpy(options, baud);
+		if (strncmp(cdev, "tty552", 6) == 0)
+			add_preferred_console("ttyS", port,
+					      baud ? options : NULL);
+		else
+			add_preferred_console("ttySC", port,
+					      baud ? options : NULL);
+	}
+#endif
+}
+
+#ifdef DEBUG
+static void __init sni_idprom_dump(void)
+{
+	int	i;
+
+	pr_debug("SNI IDProm dump:\n");
+	for (i = 0; i < 256; i++) {
+		if (i%16 == 0)
+			pr_debug("%04x ", i);
+
+		printk("%02x ", *(unsigned char *) (SNI_IDPROM_BASE + i));
+
+		if (i % 16 == 15)
+			printk("\n");
+	}
+}
+#endif
+
+void __init plat_mem_setup(void)
+{
+	int cputype;
+
+	set_io_port_base(SNI_PORT_BASE);
+//	ioport_resource.end = sni_io_resource.end;
+
+	/*
+	 * Setup (E)ISA I/O memory access stuff
+	 */
+#ifdef CONFIG_EISA
+	EISA_bus = 1;
+#endif
+
+	sni_brd_type = *(unsigned char *)SNI_IDPROM_BRDTYPE;
+	cputype = *(unsigned char *)SNI_IDPROM_CPUTYPE;
+	switch (sni_brd_type) {
+	case SNI_BRD_TOWER_OASIC:
+		switch (cputype) {
+		case SNI_CPU_M8030:
+			system_type = "RM400-330";
+			break;
+		case SNI_CPU_M8031:
+			system_type = "RM400-430";
+			break;
+		case SNI_CPU_M8037:
+			system_type = "RM400-530";
+			break;
+		case SNI_CPU_M8034:
+			system_type = "RM400-730";
+			break;
+		default:
+			system_type = "RM400-xxx";
+			break;
+		}
+		break;
+	case SNI_BRD_MINITOWER:
+		switch (cputype) {
+		case SNI_CPU_M8021:
+		case SNI_CPU_M8043:
+			system_type = "RM400-120";
+			break;
+		case SNI_CPU_M8040:
+			system_type = "RM400-220";
+			break;
+		case SNI_CPU_M8053:
+			system_type = "RM400-225";
+			break;
+		case SNI_CPU_M8050:
+			system_type = "RM400-420";
+			break;
+		default:
+			system_type = "RM400-xxx";
+			break;
+		}
+		break;
+	case SNI_BRD_PCI_TOWER:
+		system_type = "RM400-Cxx";
+		break;
+	case SNI_BRD_RM200:
+		system_type = "RM200-xxx";
+		break;
+	case SNI_BRD_PCI_MTOWER:
+		system_type = "RM300-Cxx";
+		break;
+	case SNI_BRD_PCI_DESKTOP:
+		switch (read_c0_prid() & PRID_IMP_MASK) {
+		case PRID_IMP_R4600:
+		case PRID_IMP_R4700:
+			system_type = "RM200-C20";
+			break;
+		case PRID_IMP_R5000:
+			system_type = "RM200-C40";
+			break;
+		default:
+			system_type = "RM200-Cxx";
+			break;
+		}
+		break;
+	case SNI_BRD_PCI_TOWER_CPLUS:
+		system_type = "RM400-Exx";
+		break;
+	case SNI_BRD_PCI_MTOWER_CPLUS:
+		system_type = "RM300-Exx";
+		break;
+	}
+	pr_debug("Found SNI brdtype %02x name %s\n", sni_brd_type, system_type);
+
+#ifdef DEBUG
+	sni_idprom_dump();
+#endif
+
+	switch (sni_brd_type) {
+	case SNI_BRD_10:
+	case SNI_BRD_10NEW:
+	case SNI_BRD_TOWER_OASIC:
+	case SNI_BRD_MINITOWER:
+		sni_a20r_init();
+		break;
+
+	case SNI_BRD_PCI_TOWER:
+	case SNI_BRD_PCI_TOWER_CPLUS:
+		sni_pcit_init();
+		break;
+
+	case SNI_BRD_RM200:
+		sni_rm200_init();
+		break;
+
+	case SNI_BRD_PCI_MTOWER:
+	case SNI_BRD_PCI_DESKTOP:
+	case SNI_BRD_PCI_MTOWER_CPLUS:
+		sni_pcimt_init();
+		break;
+	}
+
+	_machine_restart = sni_machine_restart;
+	pm_power_off = sni_machine_power_off;
+
+	sni_display_setup();
+	sni_console_setup();
+}
+
+#ifdef CONFIG_PCI
+
+#include <linux/pci.h>
+#include <video/vga.h>
+#include <video/cirrus.h>
+
+static void quirk_cirrus_ram_size(struct pci_dev *dev)
+{
+	u16 cmd;
+
+	/*
+	 * firmware doesn't set the ram size correct, so we
+	 * need to do it here, otherwise we get screen corruption
+	 * on older Cirrus chips
+	 */
+	pci_read_config_word(dev, PCI_COMMAND, &cmd);
+	if ((cmd & (PCI_COMMAND_IO|PCI_COMMAND_MEMORY))
+		== (PCI_COMMAND_IO|PCI_COMMAND_MEMORY)) {
+		vga_wseq(NULL, CL_SEQR6, 0x12); /* unlock all extension registers */
+		vga_wseq(NULL, CL_SEQRF, 0x18);
+	}
+}
+
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_CIRRUS, PCI_DEVICE_ID_CIRRUS_5434_8,
+			quirk_cirrus_ram_size);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_CIRRUS, PCI_DEVICE_ID_CIRRUS_5436,
+			quirk_cirrus_ram_size);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_CIRRUS, PCI_DEVICE_ID_CIRRUS_5446,
+			quirk_cirrus_ram_size);
+#endif