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, 372 insertions, 0 deletions

diff --git a/drivers/video/fbdev/clps711x-fb.c b/drivers/video/fbdev/clps711x-fb.c
new file mode 100644
index 000000000..6789773b2
--- /dev/null
+++ b/drivers/video/fbdev/clps711x-fb.c
@@ -0,0 +1,372 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Cirrus Logic CLPS711X FB driver
+ *
+ * Copyright (C) 2014 Alexander Shiyan <shc_work@mail.ru>
+ * Based on driver by Russell King <rmk@arm.linux.org.uk>
+ */
+
+#include <linux/clk.h>
+#include <linux/fb.h>
+#include <linux/io.h>
+#include <linux/lcd.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/mfd/syscon.h>
+#include <linux/mfd/syscon/clps711x.h>
+#include <linux/regulator/consumer.h>
+#include <video/of_display_timing.h>
+
+#define CLPS711X_FB_NAME	"clps711x-fb"
+#define CLPS711X_FB_BPP_MAX	(4)
+
+/* Registers relative to LCDCON */
+#define CLPS711X_LCDCON		(0x0000)
+# define LCDCON_GSEN		BIT(30)
+# define LCDCON_GSMD		BIT(31)
+#define CLPS711X_PALLSW		(0x0280)
+#define CLPS711X_PALMSW		(0x02c0)
+#define CLPS711X_FBADDR		(0x0d40)
+
+struct clps711x_fb_info {
+	struct clk		*clk;
+	void __iomem		*base;
+	struct regmap		*syscon;
+	resource_size_t		buffsize;
+	struct fb_videomode	mode;
+	struct regulator	*lcd_pwr;
+	u32			ac_prescale;
+	bool			cmap_invert;
+};
+
+static int clps711x_fb_setcolreg(u_int regno, u_int red, u_int green,
+				 u_int blue, u_int transp, struct fb_info *info)
+{
+	struct clps711x_fb_info *cfb = info->par;
+	u32 level, mask, shift;
+
+	if (regno >= BIT(info->var.bits_per_pixel))
+		return -EINVAL;
+
+	shift = 4 * (regno & 7);
+	mask  = 0xf << shift;
+	/* gray = 0.30*R + 0.58*G + 0.11*B */
+	level = (((red * 77 + green * 151 + blue * 28) >> 20) << shift) & mask;
+	if (cfb->cmap_invert)
+		level = 0xf - level;
+
+	regno = (regno < 8) ? CLPS711X_PALLSW : CLPS711X_PALMSW;
+
+	writel((readl(cfb->base + regno) & ~mask) | level, cfb->base + regno);
+
+	return 0;
+}
+
+static int clps711x_fb_check_var(struct fb_var_screeninfo *var,
+				 struct fb_info *info)
+{
+	u32 val;
+
+	if (var->bits_per_pixel < 1 ||
+	    var->bits_per_pixel > CLPS711X_FB_BPP_MAX)
+		return -EINVAL;
+
+	if (!var->pixclock)
+		return -EINVAL;
+
+	val = DIV_ROUND_UP(var->xres, 16) - 1;
+	if (val < 0x01 || val > 0x3f)
+		return -EINVAL;
+
+	val = DIV_ROUND_UP(var->yres * var->xres * var->bits_per_pixel, 128);
+	val--;
+	if (val < 0x001 || val > 0x1fff)
+		return -EINVAL;
+
+	var->transp.msb_right	= 0;
+	var->transp.offset	= 0;
+	var->transp.length	= 0;
+	var->red.msb_right	= 0;
+	var->red.offset		= 0;
+	var->red.length		= var->bits_per_pixel;
+	var->green		= var->red;
+	var->blue		= var->red;
+	var->grayscale		= var->bits_per_pixel > 1;
+
+	return 0;
+}
+
+static int clps711x_fb_set_par(struct fb_info *info)
+{
+	struct clps711x_fb_info *cfb = info->par;
+	resource_size_t size;
+	u32 lcdcon, pps;
+
+	size = (info->var.xres * info->var.yres * info->var.bits_per_pixel) / 8;
+	if (size > cfb->buffsize)
+		return -EINVAL;
+
+	switch (info->var.bits_per_pixel) {
+	case 1:
+		info->fix.visual = FB_VISUAL_MONO01;
+		break;
+	case 2:
+	case 4:
+		info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	info->fix.line_length = info->var.xres * info->var.bits_per_pixel / 8;
+	info->fix.smem_len = size;
+
+	lcdcon = (info->var.xres * info->var.yres *
+		  info->var.bits_per_pixel) / 128 - 1;
+	lcdcon |= ((info->var.xres / 16) - 1) << 13;
+	lcdcon |= (cfb->ac_prescale & 0x1f) << 25;
+
+	pps = clk_get_rate(cfb->clk) / (PICOS2KHZ(info->var.pixclock) * 1000);
+	if (pps)
+		pps--;
+	lcdcon |= (pps & 0x3f) << 19;
+
+	if (info->var.bits_per_pixel == 4)
+		lcdcon |= LCDCON_GSMD;
+	if (info->var.bits_per_pixel >= 2)
+		lcdcon |= LCDCON_GSEN;
+
+	/* LCDCON must only be changed while the LCD is disabled */
+	regmap_update_bits(cfb->syscon, SYSCON_OFFSET, SYSCON1_LCDEN, 0);
+	writel(lcdcon, cfb->base + CLPS711X_LCDCON);
+	regmap_update_bits(cfb->syscon, SYSCON_OFFSET,
+			   SYSCON1_LCDEN, SYSCON1_LCDEN);
+
+	return 0;
+}
+
+static int clps711x_fb_blank(int blank, struct fb_info *info)
+{
+	/* Return happy */
+	return 0;
+}
+
+static const struct fb_ops clps711x_fb_ops = {
+	.owner		= THIS_MODULE,
+	FB_DEFAULT_IOMEM_OPS,
+	.fb_setcolreg	= clps711x_fb_setcolreg,
+	.fb_check_var	= clps711x_fb_check_var,
+	.fb_set_par	= clps711x_fb_set_par,
+	.fb_blank	= clps711x_fb_blank,
+};
+
+static int clps711x_lcd_get_power(struct lcd_device *lcddev)
+{
+	struct clps711x_fb_info *cfb = dev_get_drvdata(&lcddev->dev);
+
+	if (!IS_ERR_OR_NULL(cfb->lcd_pwr))
+		if (!regulator_is_enabled(cfb->lcd_pwr))
+			return LCD_POWER_REDUCED;
+
+	return LCD_POWER_ON;
+}
+
+static int clps711x_lcd_set_power(struct lcd_device *lcddev, int blank)
+{
+	struct clps711x_fb_info *cfb = dev_get_drvdata(&lcddev->dev);
+
+	if (!IS_ERR_OR_NULL(cfb->lcd_pwr)) {
+		if (blank == LCD_POWER_ON) {
+			if (!regulator_is_enabled(cfb->lcd_pwr))
+				return regulator_enable(cfb->lcd_pwr);
+		} else {
+			if (regulator_is_enabled(cfb->lcd_pwr))
+				return regulator_disable(cfb->lcd_pwr);
+		}
+	}
+
+	return 0;
+}
+
+static const struct lcd_ops clps711x_lcd_ops = {
+	.get_power	= clps711x_lcd_get_power,
+	.set_power	= clps711x_lcd_set_power,
+};
+
+static int clps711x_fb_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *disp, *np = dev->of_node;
+	struct clps711x_fb_info *cfb;
+	struct lcd_device *lcd;
+	struct fb_info *info;
+	struct resource *res;
+	int ret = -ENOENT;
+	u32 val;
+
+	if (fb_get_options(CLPS711X_FB_NAME, NULL))
+		return -ENODEV;
+
+	info = framebuffer_alloc(sizeof(*cfb), dev);
+	if (!info)
+		return -ENOMEM;
+
+	cfb = info->par;
+	platform_set_drvdata(pdev, info);
+
+	cfb->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(cfb->base)) {
+		ret = PTR_ERR(cfb->base);
+		goto out_fb_release;
+	}
+
+	info->fix.mmio_start = res->start;
+	info->fix.mmio_len = resource_size(res);
+
+	info->screen_base = devm_platform_get_and_ioremap_resource(pdev, 1, &res);
+	if (IS_ERR(info->screen_base)) {
+		ret = PTR_ERR(info->screen_base);
+		goto out_fb_release;
+	}
+
+	/* Physical address should be aligned to 256 MiB */
+	if (res->start & 0x0fffffff) {
+		ret = -EINVAL;
+		goto out_fb_release;
+	}
+
+	cfb->buffsize = resource_size(res);
+	info->fix.smem_start = res->start;
+
+	cfb->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(cfb->clk)) {
+		ret = PTR_ERR(cfb->clk);
+		goto out_fb_release;
+	}
+
+	cfb->syscon = syscon_regmap_lookup_by_phandle(np, "syscon");
+	if (IS_ERR(cfb->syscon)) {
+		ret = PTR_ERR(cfb->syscon);
+		goto out_fb_release;
+	}
+
+	disp = of_parse_phandle(np, "display", 0);
+	if (!disp) {
+		dev_err(&pdev->dev, "No display defined\n");
+		ret = -ENODATA;
+		goto out_fb_release;
+	}
+
+	ret = of_get_fb_videomode(disp, &cfb->mode, OF_USE_NATIVE_MODE);
+	if (ret) {
+		of_node_put(disp);
+		goto out_fb_release;
+	}
+
+	of_property_read_u32(disp, "ac-prescale", &cfb->ac_prescale);
+	cfb->cmap_invert = of_property_read_bool(disp, "cmap-invert");
+
+	ret = of_property_read_u32(disp, "bits-per-pixel",
+				   &info->var.bits_per_pixel);
+	of_node_put(disp);
+	if (ret)
+		goto out_fb_release;
+
+	/* Force disable LCD on any mismatch */
+	if (info->fix.smem_start != (readb(cfb->base + CLPS711X_FBADDR) << 28))
+		regmap_update_bits(cfb->syscon, SYSCON_OFFSET,
+				   SYSCON1_LCDEN, 0);
+
+	ret = regmap_read(cfb->syscon, SYSCON_OFFSET, &val);
+	if (ret)
+		goto out_fb_release;
+
+	if (!(val & SYSCON1_LCDEN)) {
+		/* Setup start FB address */
+		writeb(info->fix.smem_start >> 28, cfb->base + CLPS711X_FBADDR);
+		/* Clean FB memory */
+		memset_io(info->screen_base, 0, cfb->buffsize);
+	}
+
+	cfb->lcd_pwr = devm_regulator_get(dev, "lcd");
+	if (PTR_ERR(cfb->lcd_pwr) == -EPROBE_DEFER) {
+		ret = -EPROBE_DEFER;
+		goto out_fb_release;
+	}
+
+	info->fbops = &clps711x_fb_ops;
+	info->var.activate = FB_ACTIVATE_FORCE | FB_ACTIVATE_NOW;
+	info->var.height = -1;
+	info->var.width = -1;
+	info->var.vmode = FB_VMODE_NONINTERLACED;
+	info->fix.type = FB_TYPE_PACKED_PIXELS;
+	info->fix.accel = FB_ACCEL_NONE;
+	strscpy(info->fix.id, CLPS711X_FB_NAME, sizeof(info->fix.id));
+	fb_videomode_to_var(&info->var, &cfb->mode);
+
+	ret = fb_alloc_cmap(&info->cmap, BIT(CLPS711X_FB_BPP_MAX), 0);
+	if (ret)
+		goto out_fb_release;
+
+	ret = fb_set_var(info, &info->var);
+	if (ret)
+		goto out_fb_dealloc_cmap;
+
+	lcd = devm_lcd_device_register(dev, "clps711x-lcd", dev, cfb,
+				       &clps711x_lcd_ops);
+	if (IS_ERR(lcd)) {
+		ret = PTR_ERR(lcd);
+		goto out_fb_dealloc_cmap;
+	}
+
+	info->lcd_dev = lcd;
+
+	ret = register_framebuffer(info);
+	if (ret)
+		goto out_fb_dealloc_cmap;
+
+	return 0;
+
+out_fb_dealloc_cmap:
+	regmap_update_bits(cfb->syscon, SYSCON_OFFSET, SYSCON1_LCDEN, 0);
+	fb_dealloc_cmap(&info->cmap);
+
+out_fb_release:
+	framebuffer_release(info);
+
+	return ret;
+}
+
+static void clps711x_fb_remove(struct platform_device *pdev)
+{
+	struct fb_info *info = platform_get_drvdata(pdev);
+	struct clps711x_fb_info *cfb = info->par;
+
+	regmap_update_bits(cfb->syscon, SYSCON_OFFSET, SYSCON1_LCDEN, 0);
+
+	unregister_framebuffer(info);
+	fb_dealloc_cmap(&info->cmap);
+	framebuffer_release(info);
+}
+
+static const struct of_device_id clps711x_fb_dt_ids[] = {
+	{ .compatible = "cirrus,ep7209-fb", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, clps711x_fb_dt_ids);
+
+static struct platform_driver clps711x_fb_driver = {
+	.driver	= {
+		.name		= CLPS711X_FB_NAME,
+		.of_match_table	= clps711x_fb_dt_ids,
+	},
+	.probe	= clps711x_fb_probe,
+	.remove	= clps711x_fb_remove,
+};
+module_platform_driver(clps711x_fb_driver);
+
+MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
+MODULE_DESCRIPTION("Cirrus Logic CLPS711X FB driver");
+MODULE_LICENSE("GPL");