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, 253 insertions, 0 deletions

diff --git a/drivers/clk/qcom/clk-hfpll.c b/drivers/clk/qcom/clk-hfpll.c
new file mode 100644
index 000000000..9e9118d24
--- /dev/null
+++ b/drivers/clk/qcom/clk-hfpll.c
@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018, The Linux Foundation. All rights reserved.
+
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/regmap.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/clk-provider.h>
+#include <linux/spinlock.h>
+
+#include "clk-regmap.h"
+#include "clk-hfpll.h"
+
+#define PLL_OUTCTRL	BIT(0)
+#define PLL_BYPASSNL	BIT(1)
+#define PLL_RESET_N	BIT(2)
+
+/* Initialize a HFPLL at a given rate and enable it. */
+static void __clk_hfpll_init_once(struct clk_hw *hw)
+{
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	struct hfpll_data const *hd = h->d;
+	struct regmap *regmap = h->clkr.regmap;
+
+	if (likely(h->init_done))
+		return;
+
+	/* Configure PLL parameters for integer mode. */
+	if (hd->config_val)
+		regmap_write(regmap, hd->config_reg, hd->config_val);
+	regmap_write(regmap, hd->m_reg, 0);
+	regmap_write(regmap, hd->n_reg, 1);
+
+	if (hd->user_reg) {
+		u32 regval = hd->user_val;
+		unsigned long rate;
+
+		rate = clk_hw_get_rate(hw);
+
+		/* Pick the right VCO. */
+		if (hd->user_vco_mask && rate > hd->low_vco_max_rate)
+			regval |= hd->user_vco_mask;
+		regmap_write(regmap, hd->user_reg, regval);
+	}
+
+	/* Write L_VAL from conf if it exist */
+	if (hd->l_val)
+		regmap_write(regmap, hd->l_reg, hd->l_val);
+
+	if (hd->droop_reg)
+		regmap_write(regmap, hd->droop_reg, hd->droop_val);
+
+	h->init_done = true;
+}
+
+static void __clk_hfpll_enable(struct clk_hw *hw)
+{
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	struct hfpll_data const *hd = h->d;
+	struct regmap *regmap = h->clkr.regmap;
+	u32 val;
+
+	__clk_hfpll_init_once(hw);
+
+	/* Disable PLL bypass mode. */
+	regmap_update_bits(regmap, hd->mode_reg, PLL_BYPASSNL, PLL_BYPASSNL);
+
+	/*
+	 * H/W requires a 5us delay between disabling the bypass and
+	 * de-asserting the reset. Delay 10us just to be safe.
+	 */
+	udelay(10);
+
+	/* De-assert active-low PLL reset. */
+	regmap_update_bits(regmap, hd->mode_reg, PLL_RESET_N, PLL_RESET_N);
+
+	/* Wait for PLL to lock. */
+	if (hd->status_reg)
+		/*
+		 * Busy wait. Should never timeout, we add a timeout to
+		 * prevent any sort of stall.
+		 */
+		regmap_read_poll_timeout(regmap, hd->status_reg, val,
+					 !(val & BIT(hd->lock_bit)), 0,
+					 100 * USEC_PER_MSEC);
+	else
+		udelay(60);
+
+	/* Enable PLL output. */
+	regmap_update_bits(regmap, hd->mode_reg, PLL_OUTCTRL, PLL_OUTCTRL);
+}
+
+/* Enable an already-configured HFPLL. */
+static int clk_hfpll_enable(struct clk_hw *hw)
+{
+	unsigned long flags;
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	struct hfpll_data const *hd = h->d;
+	struct regmap *regmap = h->clkr.regmap;
+	u32 mode;
+
+	spin_lock_irqsave(&h->lock, flags);
+	regmap_read(regmap, hd->mode_reg, &mode);
+	if (!(mode & (PLL_BYPASSNL | PLL_RESET_N | PLL_OUTCTRL)))
+		__clk_hfpll_enable(hw);
+	spin_unlock_irqrestore(&h->lock, flags);
+
+	return 0;
+}
+
+static void __clk_hfpll_disable(struct clk_hfpll *h)
+{
+	struct hfpll_data const *hd = h->d;
+	struct regmap *regmap = h->clkr.regmap;
+
+	/*
+	 * Disable the PLL output, disable test mode, enable the bypass mode,
+	 * and assert the reset.
+	 */
+	regmap_update_bits(regmap, hd->mode_reg,
+			   PLL_BYPASSNL | PLL_RESET_N | PLL_OUTCTRL, 0);
+}
+
+static void clk_hfpll_disable(struct clk_hw *hw)
+{
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	unsigned long flags;
+
+	spin_lock_irqsave(&h->lock, flags);
+	__clk_hfpll_disable(h);
+	spin_unlock_irqrestore(&h->lock, flags);
+}
+
+static int clk_hfpll_determine_rate(struct clk_hw *hw, struct clk_rate_request *req)
+{
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	struct hfpll_data const *hd = h->d;
+	unsigned long rrate;
+
+	req->rate = clamp(req->rate, hd->min_rate, hd->max_rate);
+
+	rrate = DIV_ROUND_UP(req->rate, req->best_parent_rate) * req->best_parent_rate;
+	if (rrate > hd->max_rate)
+		rrate -= req->best_parent_rate;
+
+	req->rate = rrate;
+	return 0;
+}
+
+/*
+ * For optimization reasons, assumes no downstream clocks are actively using
+ * it.
+ */
+static int clk_hfpll_set_rate(struct clk_hw *hw, unsigned long rate,
+			      unsigned long parent_rate)
+{
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	struct hfpll_data const *hd = h->d;
+	struct regmap *regmap = h->clkr.regmap;
+	unsigned long flags;
+	u32 l_val, val;
+	bool enabled;
+
+	l_val = rate / parent_rate;
+
+	spin_lock_irqsave(&h->lock, flags);
+
+	enabled = clk_hw_is_enabled(hw);
+	if (enabled)
+		__clk_hfpll_disable(h);
+
+	/* Pick the right VCO. */
+	if (hd->user_reg && hd->user_vco_mask) {
+		regmap_read(regmap, hd->user_reg, &val);
+		if (rate <= hd->low_vco_max_rate)
+			val &= ~hd->user_vco_mask;
+		else
+			val |= hd->user_vco_mask;
+		regmap_write(regmap, hd->user_reg, val);
+	}
+
+	regmap_write(regmap, hd->l_reg, l_val);
+
+	if (enabled)
+		__clk_hfpll_enable(hw);
+
+	spin_unlock_irqrestore(&h->lock, flags);
+
+	return 0;
+}
+
+static unsigned long clk_hfpll_recalc_rate(struct clk_hw *hw,
+					   unsigned long parent_rate)
+{
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	struct hfpll_data const *hd = h->d;
+	struct regmap *regmap = h->clkr.regmap;
+	u32 l_val;
+
+	regmap_read(regmap, hd->l_reg, &l_val);
+
+	return l_val * parent_rate;
+}
+
+static int clk_hfpll_init(struct clk_hw *hw)
+{
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	struct hfpll_data const *hd = h->d;
+	struct regmap *regmap = h->clkr.regmap;
+	u32 mode, status;
+
+	regmap_read(regmap, hd->mode_reg, &mode);
+	if (mode != (PLL_BYPASSNL | PLL_RESET_N | PLL_OUTCTRL)) {
+		__clk_hfpll_init_once(hw);
+		return 0;
+	}
+
+	if (hd->status_reg) {
+		regmap_read(regmap, hd->status_reg, &status);
+		if (!(status & BIT(hd->lock_bit))) {
+			WARN(1, "HFPLL %s is ON, but not locked!\n",
+			     clk_hw_get_name(hw));
+			clk_hfpll_disable(hw);
+			__clk_hfpll_init_once(hw);
+		}
+	}
+
+	return 0;
+}
+
+static int hfpll_is_enabled(struct clk_hw *hw)
+{
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	struct hfpll_data const *hd = h->d;
+	struct regmap *regmap = h->clkr.regmap;
+	u32 mode;
+
+	regmap_read(regmap, hd->mode_reg, &mode);
+	mode &= 0x7;
+	return mode == (PLL_BYPASSNL | PLL_RESET_N | PLL_OUTCTRL);
+}
+
+const struct clk_ops clk_ops_hfpll = {
+	.enable = clk_hfpll_enable,
+	.disable = clk_hfpll_disable,
+	.is_enabled = hfpll_is_enabled,
+	.determine_rate = clk_hfpll_determine_rate,
+	.set_rate = clk_hfpll_set_rate,
+	.recalc_rate = clk_hfpll_recalc_rate,
+	.init = clk_hfpll_init,
+};
+EXPORT_SYMBOL_GPL(clk_ops_hfpll);