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, 110 insertions, 0 deletions

diff --git a/drivers/dma/ste_dma40.h b/drivers/dma/ste_dma40.h
new file mode 100644
index 000000000..a90c786ac
--- /dev/null
+++ b/drivers/dma/ste_dma40.h
@@ -0,0 +1,110 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef STE_DMA40_H
+#define STE_DMA40_H
+
+/*
+ * Maximum size for a single dma descriptor
+ * Size is limited to 16 bits.
+ * Size is in the units of addr-widths (1,2,4,8 bytes)
+ * Larger transfers will be split up to multiple linked desc
+ */
+#define STEDMA40_MAX_SEG_SIZE 0xFFFF
+
+/* dev types for memcpy */
+#define STEDMA40_DEV_DST_MEMORY (-1)
+#define	STEDMA40_DEV_SRC_MEMORY (-1)
+
+enum stedma40_mode {
+	STEDMA40_MODE_LOGICAL = 0,
+	STEDMA40_MODE_PHYSICAL,
+	STEDMA40_MODE_OPERATION,
+};
+
+enum stedma40_mode_opt {
+	STEDMA40_PCHAN_BASIC_MODE = 0,
+	STEDMA40_LCHAN_SRC_LOG_DST_LOG = 0,
+	STEDMA40_PCHAN_MODULO_MODE,
+	STEDMA40_PCHAN_DOUBLE_DST_MODE,
+	STEDMA40_LCHAN_SRC_PHY_DST_LOG,
+	STEDMA40_LCHAN_SRC_LOG_DST_PHY,
+};
+
+#define STEDMA40_ESIZE_8_BIT  0x0
+#define STEDMA40_ESIZE_16_BIT 0x1
+#define STEDMA40_ESIZE_32_BIT 0x2
+#define STEDMA40_ESIZE_64_BIT 0x3
+
+/* The value 4 indicates that PEN-reg shall be set to 0 */
+#define STEDMA40_PSIZE_PHY_1  0x4
+#define STEDMA40_PSIZE_PHY_2  0x0
+#define STEDMA40_PSIZE_PHY_4  0x1
+#define STEDMA40_PSIZE_PHY_8  0x2
+#define STEDMA40_PSIZE_PHY_16 0x3
+
+/*
+ * The number of elements differ in logical and
+ * physical mode
+ */
+#define STEDMA40_PSIZE_LOG_1  STEDMA40_PSIZE_PHY_2
+#define STEDMA40_PSIZE_LOG_4  STEDMA40_PSIZE_PHY_4
+#define STEDMA40_PSIZE_LOG_8  STEDMA40_PSIZE_PHY_8
+#define STEDMA40_PSIZE_LOG_16 STEDMA40_PSIZE_PHY_16
+
+/* Maximum number of possible physical channels */
+#define STEDMA40_MAX_PHYS 32
+
+enum stedma40_flow_ctrl {
+	STEDMA40_NO_FLOW_CTRL,
+	STEDMA40_FLOW_CTRL,
+};
+
+/**
+ * struct stedma40_half_channel_info - dst/src channel configuration
+ *
+ * @big_endian: true if the src/dst should be read as big endian
+ * @data_width: Data width of the src/dst hardware
+ * @p_size: Burst size
+ * @flow_ctrl: Flow control on/off.
+ */
+struct stedma40_half_channel_info {
+	bool big_endian;
+	enum dma_slave_buswidth data_width;
+	int psize;
+	enum stedma40_flow_ctrl flow_ctrl;
+};
+
+/**
+ * struct stedma40_chan_cfg - Structure to be filled by client drivers.
+ *
+ * @dir: MEM 2 MEM, PERIPH 2 MEM , MEM 2 PERIPH, PERIPH 2 PERIPH
+ * @high_priority: true if high-priority
+ * @realtime: true if realtime mode is to be enabled.  Only available on DMA40
+ * version 3+, i.e DB8500v2+
+ * @mode: channel mode: physical, logical, or operation
+ * @mode_opt: options for the chosen channel mode
+ * @dev_type: src/dst device type (driver uses dir to figure out which)
+ * @src_info: Parameters for dst half channel
+ * @dst_info: Parameters for dst half channel
+ * @use_fixed_channel: if true, use physical channel specified by phy_channel
+ * @phy_channel: physical channel to use, only if use_fixed_channel is true
+ *
+ * This structure has to be filled by the client drivers.
+ * It is recommended to do all dma configurations for clients in the machine.
+ *
+ */
+struct stedma40_chan_cfg {
+	enum dma_transfer_direction		 dir;
+	bool					 high_priority;
+	bool					 realtime;
+	enum stedma40_mode			 mode;
+	enum stedma40_mode_opt			 mode_opt;
+	int					 dev_type;
+	struct stedma40_half_channel_info	 src_info;
+	struct stedma40_half_channel_info	 dst_info;
+
+	bool					 use_fixed_channel;
+	int					 phy_channel;
+};
+
+#endif /* STE_DMA40_H */