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, 81 insertions, 0 deletions

diff --git a/Documentation/driver-api/backlight/lp855x-driver.rst b/Documentation/driver-api/backlight/lp855x-driver.rst
new file mode 100644
index 000000000..1e0b224fc
--- /dev/null
+++ b/Documentation/driver-api/backlight/lp855x-driver.rst
@@ -0,0 +1,81 @@
+====================
+Kernel driver lp855x
+====================
+
+Backlight driver for LP855x ICs
+
+Supported chips:
+
+	Texas Instruments LP8550, LP8551, LP8552, LP8553, LP8555, LP8556 and
+	LP8557
+
+Author: Milo(Woogyom) Kim <milo.kim@ti.com>
+
+Description
+-----------
+
+* Brightness control
+
+  Brightness can be controlled by the pwm input or the i2c command.
+  The lp855x driver supports both cases.
+
+* Device attributes
+
+  1) bl_ctl_mode
+
+  Backlight control mode.
+
+  Value: pwm based or register based
+
+  2) chip_id
+
+  The lp855x chip id.
+
+  Value: lp8550/lp8551/lp8552/lp8553/lp8555/lp8556/lp8557
+
+Platform data for lp855x
+------------------------
+
+For supporting platform specific data, the lp855x platform data can be used.
+
+* name:
+	Backlight driver name. If it is not defined, default name is set.
+* device_control:
+	Value of DEVICE CONTROL register.
+* initial_brightness:
+	Initial value of backlight brightness.
+* period_ns:
+	Platform specific PWM period value. unit is nano.
+	Only valid when brightness is pwm input mode.
+* size_program:
+	Total size of lp855x_rom_data.
+* rom_data:
+	List of new eeprom/eprom registers.
+
+Examples
+========
+
+1) lp8552 platform data: i2c register mode with new eeprom data::
+
+    #define EEPROM_A5_ADDR	0xA5
+    #define EEPROM_A5_VAL	0x4f	/* EN_VSYNC=0 */
+
+    static struct lp855x_rom_data lp8552_eeprom_arr[] = {
+	{EEPROM_A5_ADDR, EEPROM_A5_VAL},
+    };
+
+    static struct lp855x_platform_data lp8552_pdata = {
+	.name = "lcd-bl",
+	.device_control = I2C_CONFIG(LP8552),
+	.initial_brightness = INITIAL_BRT,
+	.size_program = ARRAY_SIZE(lp8552_eeprom_arr),
+	.rom_data = lp8552_eeprom_arr,
+    };
+
+2) lp8556 platform data: pwm input mode with default rom data::
+
+    static struct lp855x_platform_data lp8556_pdata = {
+	.device_control = PWM_CONFIG(LP8556),
+	.initial_brightness = INITIAL_BRT,
+	.period_ns = 1000000,
+    };