Mingwei Zhang 39b0235284 KVM: SEV: add cache flush to solve SEV cache incoherency issues ... commit 683412ccf6 upstream. Flush the CPU caches when memory is reclaimed from an SEV guest (where reclaim also includes it being unmapped from KVM's memslots). Due to lack of coherency for SEV encrypted memory, failure to flush results in silent data corruption if userspace is malicious/broken and doesn't ensure SEV guest memory is properly pinned and unpinned. Cache coherency is not enforced across the VM boundary in SEV (AMD APM vol.2 Section 15.34.7). Confidential cachelines, generated by confidential VM guests have to be explicitly flushed on the host side. If a memory page containing dirty confidential cachelines was released by VM and reallocated to another user, the cachelines may corrupt the new user at a later time. KVM takes a shortcut by assuming all confidential memory remain pinned until the end of VM lifetime. Therefore, KVM does not flush cache at mmu_notifier invalidation events. Because of this incorrect assumption and the lack of cache flushing, malicous userspace can crash the host kernel: creating a malicious VM and continuously allocates/releases unpinned confidential memory pages when the VM is running. Add cache flush operations to mmu_notifier operations to ensure that any physical memory leaving the guest VM get flushed. In particular, hook mmu_notifier_invalidate_range_start and mmu_notifier_release events and flush cache accordingly. The hook after releasing the mmu lock to avoid contention with other vCPUs. Cc: stable@vger.kernel.org Suggested-by: Sean Christpherson <seanjc@google.com> Reported-by: Mingwei Zhang <mizhang@google.com> Signed-off-by: Mingwei Zhang <mizhang@google.com> Message-Id: <20220421031407.2516575-4-mizhang@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> [OP: adjusted KVM_X86_OP_OPTIONAL() -> KVM_X86_OP_NULL, applied kvm_arch_guest_memory_reclaimed() call in kvm_set_memslot()] Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2022-09-23 14:15:52 +02:00
..
async_pf.c	mm/gup: remove task_struct pointer for all gup code	2020-08-12 10:58:04 -07:00
async_pf.h	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 504	2019-06-19 17:09:56 +02:00
binary_stats.c	KVM: stats: remove dead stores	2021-08-13 03:35:15 -04:00
coalesced_mmio.c	KVM: mmio: Fix use-after-free Read in kvm_vm_ioctl_unregister_coalesced_mmio	2021-07-14 12:17:56 -04:00
coalesced_mmio.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
dirty_ring.c	KVM: Drop unused kvm_dirty_gfn_invalid()	2021-09-06 08:23:46 -04:00
eventfd.c	KVM: eventfd: Fix false positive RCU usage warning	2022-02-16 12:56:16 +01:00
irqchip.c	KVM/arm updates for 5.3	2019-07-11 15:14:16 +02:00
Kconfig	kvm: add PM-notifier	2021-06-17 13:09:32 -04:00
kvm_main.c	KVM: SEV: add cache flush to solve SEV cache incoherency issues	2022-09-23 14:15:52 +02:00
mmu_lock.h	KVM: x86/mmu: Use an rwlock for the x86 MMU	2021-02-04 05:27:43 -05:00
vfio.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500	2019-06-19 17:09:55 +02:00
vfio.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00