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/video/fbdev/sunxvr2500.c b/drivers/video/fbdev/sunxvr2500.c
new file mode 100644
index 000000000..b7587ff4d
--- /dev/null
+++ b/drivers/video/fbdev/sunxvr2500.c
@@ -0,0 +1,250 @@
+/* sunxvr2500.c: Sun 3DLABS XVR-2500 et al. fb driver for sparc64 systems
+ *
+ * License: GPL
+ *
+ * Copyright (C) 2007 David S. Miller (davem@davemloft.net)
+ */
+
+#include <linux/aperture.h>
+#include <linux/kernel.h>
+#include <linux/fb.h>
+#include <linux/pci.h>
+#include <linux/init.h>
+#include <linux/of.h>
+
+#include <asm/io.h>
+
+struct s3d_info {
+	struct fb_info		*info;
+	struct pci_dev		*pdev;
+
+	char __iomem		*fb_base;
+	unsigned long		fb_base_phys;
+
+	struct device_node	*of_node;
+
+	unsigned int		width;
+	unsigned int		height;
+	unsigned int		depth;
+	unsigned int		fb_size;
+
+	u32			pseudo_palette[16];
+};
+
+static int s3d_get_props(struct s3d_info *sp)
+{
+	sp->width = of_getintprop_default(sp->of_node, "width", 0);
+	sp->height = of_getintprop_default(sp->of_node, "height", 0);
+	sp->depth = of_getintprop_default(sp->of_node, "depth", 8);
+
+	if (!sp->width || !sp->height) {
+		pci_err(sp->pdev, "Critical properties missing\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int s3d_setcolreg(unsigned regno,
+			 unsigned red, unsigned green, unsigned blue,
+			 unsigned transp, struct fb_info *info)
+{
+	u32 value;
+
+	if (regno < 16) {
+		red >>= 8;
+		green >>= 8;
+		blue >>= 8;
+
+		value = (blue << 24) | (green << 16) | (red << 8);
+		((u32 *)info->pseudo_palette)[regno] = value;
+	}
+
+	return 0;
+}
+
+static const struct fb_ops s3d_ops = {
+	.owner			= THIS_MODULE,
+	FB_DEFAULT_IOMEM_OPS,
+	.fb_setcolreg		= s3d_setcolreg,
+};
+
+static int s3d_set_fbinfo(struct s3d_info *sp)
+{
+	struct fb_info *info = sp->info;
+	struct fb_var_screeninfo *var = &info->var;
+
+	info->fbops = &s3d_ops;
+	info->screen_base = sp->fb_base;
+	info->screen_size = sp->fb_size;
+
+	info->pseudo_palette = sp->pseudo_palette;
+
+	/* Fill fix common fields */
+	strscpy(info->fix.id, "s3d", sizeof(info->fix.id));
+        info->fix.smem_start = sp->fb_base_phys;
+        info->fix.smem_len = sp->fb_size;
+        info->fix.type = FB_TYPE_PACKED_PIXELS;
+	if (sp->depth == 32 || sp->depth == 24)
+		info->fix.visual = FB_VISUAL_TRUECOLOR;
+	else
+		info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
+
+	var->xres = sp->width;
+	var->yres = sp->height;
+	var->xres_virtual = var->xres;
+	var->yres_virtual = var->yres;
+	var->bits_per_pixel = sp->depth;
+
+	var->red.offset = 8;
+	var->red.length = 8;
+	var->green.offset = 16;
+	var->green.length = 8;
+	var->blue.offset = 24;
+	var->blue.length = 8;
+	var->transp.offset = 0;
+	var->transp.length = 0;
+
+	if (fb_alloc_cmap(&info->cmap, 256, 0)) {
+		pci_err(sp->pdev, "Cannot allocate color map\n");
+		return -ENOMEM;
+	}
+
+        return 0;
+}
+
+static int s3d_pci_register(struct pci_dev *pdev,
+			    const struct pci_device_id *ent)
+{
+	struct fb_info *info;
+	struct s3d_info *sp;
+	int err;
+
+	err = aperture_remove_conflicting_pci_devices(pdev, "s3dfb");
+	if (err)
+		return err;
+
+	err = pci_enable_device(pdev);
+	if (err < 0) {
+		pci_err(pdev, "Cannot enable PCI device\n");
+		goto err_out;
+	}
+
+	info = framebuffer_alloc(sizeof(struct s3d_info), &pdev->dev);
+	if (!info) {
+		err = -ENOMEM;
+		goto err_disable;
+	}
+
+	sp = info->par;
+	sp->info = info;
+	sp->pdev = pdev;
+	sp->of_node = pci_device_to_OF_node(pdev);
+	if (!sp->of_node) {
+		pci_err(pdev, "Cannot find OF node\n");
+		err = -ENODEV;
+		goto err_release_fb;
+	}
+
+	sp->fb_base_phys = pci_resource_start (pdev, 1);
+
+	err = pci_request_region(pdev, 1, "s3d framebuffer");
+	if (err < 0) {
+		pci_err(pdev, "Cannot request region 1\n");
+		goto err_release_fb;
+	}
+
+	err = s3d_get_props(sp);
+	if (err)
+		goto err_release_pci;
+
+	/* XXX 'linebytes' is often wrong, it is equal to the width
+	 * XXX with depth of 32 on my XVR-2500 which is clearly not
+	 * XXX right.  So we don't try to use it.
+	 */
+	switch (sp->depth) {
+	case 8:
+		info->fix.line_length = sp->width;
+		break;
+	case 16:
+		info->fix.line_length = sp->width * 2;
+		break;
+	case 24:
+		info->fix.line_length = sp->width * 3;
+		break;
+	case 32:
+		info->fix.line_length = sp->width * 4;
+		break;
+	}
+	sp->fb_size = info->fix.line_length * sp->height;
+
+	sp->fb_base = ioremap(sp->fb_base_phys, sp->fb_size);
+	if (!sp->fb_base) {
+		err = -ENOMEM;
+		goto err_release_pci;
+	}
+
+	err = s3d_set_fbinfo(sp);
+	if (err)
+		goto err_unmap_fb;
+
+	pci_set_drvdata(pdev, info);
+
+	pci_info(pdev, "Found device\n");
+
+	err = register_framebuffer(info);
+	if (err < 0) {
+		pci_err(pdev, "Could not register framebuffer\n");
+		goto err_unmap_fb;
+	}
+
+	return 0;
+
+err_unmap_fb:
+	iounmap(sp->fb_base);
+
+err_release_pci:
+	pci_release_region(pdev, 1);
+
+err_release_fb:
+        framebuffer_release(info);
+
+err_disable:
+	pci_disable_device(pdev);
+
+err_out:
+	return err;
+}
+
+static const struct pci_device_id s3d_pci_table[] = {
+	{	PCI_DEVICE(PCI_VENDOR_ID_3DLABS, 0x002c),	},
+	{	PCI_DEVICE(PCI_VENDOR_ID_3DLABS, 0x002d),	},
+	{	PCI_DEVICE(PCI_VENDOR_ID_3DLABS, 0x002e),	},
+	{	PCI_DEVICE(PCI_VENDOR_ID_3DLABS, 0x002f),	},
+	{	PCI_DEVICE(PCI_VENDOR_ID_3DLABS, 0x0030),	},
+	{	PCI_DEVICE(PCI_VENDOR_ID_3DLABS, 0x0031),	},
+	{	PCI_DEVICE(PCI_VENDOR_ID_3DLABS, 0x0032),	},
+	{	PCI_DEVICE(PCI_VENDOR_ID_3DLABS, 0x0033),	},
+	{ 0, }
+};
+
+static struct pci_driver s3d_driver = {
+	.driver = {
+		.suppress_bind_attrs = true,
+	},
+	.name		= "s3d",
+	.id_table	= s3d_pci_table,
+	.probe		= s3d_pci_register,
+};
+
+static int __init s3d_init(void)
+{
+	if (fb_modesetting_disabled("s3d"))
+		return -ENODEV;
+
+	if (fb_get_options("s3d", NULL))
+		return -ENODEV;
+
+	return pci_register_driver(&s3d_driver);
+}
+device_initcall(s3d_init);