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, 68 insertions, 0 deletions

diff --git a/Documentation/fb/arkfb.rst b/Documentation/fb/arkfb.rst
new file mode 100644
index 000000000..aeca8773d
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+++ b/Documentation/fb/arkfb.rst
@@ -0,0 +1,68 @@
+========================================
+arkfb - fbdev driver for ARK Logic chips
+========================================
+
+
+Supported Hardware
+==================
+
+	ARK 2000PV chip
+	ICS 5342 ramdac
+
+	- only BIOS initialized VGA devices supported
+	- probably not working on big endian
+
+
+Supported Features
+==================
+
+	*  4 bpp pseudocolor modes (with 18bit palette, two variants)
+	*  8 bpp pseudocolor mode (with 18bit palette)
+	* 16 bpp truecolor modes (RGB 555 and RGB 565)
+	* 24 bpp truecolor mode (RGB 888)
+	* 32 bpp truecolor mode (RGB 888)
+	* text mode (activated by bpp = 0)
+	* doublescan mode variant (not available in text mode)
+	* panning in both directions
+	* suspend/resume support
+
+Text mode is supported even in higher resolutions, but there is limitation to
+lower pixclocks (i got maximum about 70 MHz, it is dependent on specific
+hardware). This limitation is not enforced by driver. Text mode supports 8bit
+wide fonts only (hardware limitation) and 16bit tall fonts (driver
+limitation). Unfortunately character attributes (like color) in text mode are
+broken for unknown reason, so its usefulness is limited.
+
+There are two 4 bpp modes. First mode (selected if nonstd == 0) is mode with
+packed pixels, high nibble first. Second mode (selected if nonstd == 1) is mode
+with interleaved planes (1 byte interleave), MSB first. Both modes support
+8bit wide fonts only (driver limitation).
+
+Suspend/resume works on systems that initialize video card during resume and
+if device is active (for example used by fbcon).
+
+
+Missing Features
+================
+(alias TODO list)
+
+	* secondary (not initialized by BIOS) device support
+	* big endian support
+	* DPMS support
+	* MMIO support
+	* interlaced mode variant
+	* support for fontwidths != 8 in 4 bpp modes
+	* support for fontheight != 16 in text mode
+	* hardware cursor
+	* vsync synchronization
+	* feature connector support
+	* acceleration support (8514-like 2D)
+
+
+Known bugs
+==========
+
+	* character attributes (and cursor) in text mode are broken
+
+--
+Ondrej Zajicek <santiago@crfreenet.org>