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, 56 insertions, 0 deletions

diff --git a/drivers/cache/Kconfig b/drivers/cache/Kconfig
new file mode 100644
index 000000000..1518449d4
--- /dev/null
+++ b/drivers/cache/Kconfig
@@ -0,0 +1,56 @@
+# SPDX-License-Identifier: GPL-2.0
+
+menuconfig CACHEMAINT_FOR_DMA
+	bool "Cache management for noncoherent DMA"
+	depends on RISCV
+	default y
+	help
+	  These drivers implement support for noncoherent DMA master devices
+	  on platforms that lack the standard CPU interfaces for this.
+
+if CACHEMAINT_FOR_DMA
+
+config AX45MP_L2_CACHE
+	bool "Andes Technology AX45MP L2 Cache controller"
+	select RISCV_NONSTANDARD_CACHE_OPS
+	help
+	  Support for the L2 cache controller on Andes Technology AX45MP platforms.
+
+config SIFIVE_CCACHE
+	bool "Sifive Composable Cache controller"
+	depends on ARCH_SIFIVE || ARCH_STARFIVE
+	help
+	  Support for the composable cache controller on SiFive platforms.
+
+config STARFIVE_STARLINK_CACHE
+	bool "StarFive StarLink Cache controller"
+	depends on ARCH_STARFIVE
+	depends on 64BIT
+	select RISCV_DMA_NONCOHERENT
+	select RISCV_NONSTANDARD_CACHE_OPS
+	help
+	  Support for the StarLink cache controller IP from StarFive.
+
+endif #CACHEMAINT_FOR_DMA
+
+menuconfig CACHEMAINT_FOR_HOTPLUG
+	bool "Cache management for memory hot plug like operations"
+	depends on GENERIC_CPU_CACHE_MAINTENANCE
+	help
+	  These drivers implement cache management for flows where it is necessary
+	  to flush data from all host caches.
+
+if CACHEMAINT_FOR_HOTPLUG
+
+config HISI_SOC_HHA
+	tristate "HiSilicon Hydra Home Agent (HHA) device driver"
+	depends on (ARM64 && ACPI) || COMPILE_TEST
+	help
+	  The Hydra Home Agent (HHA) is responsible for cache coherency
+	  on the SoC. This drivers enables the cache maintenance functions of
+	  the HHA.
+
+	  This driver can be built as a module. If so, the module will be
+	  called hisi_soc_hha.
+
+endif #CACHEMAINT_FOR_HOTPLUG