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KVM_PRE_FAULT_MEMORY for an SNP guest can race with sev_gmem_post_populate() in bad ways. The following sequence for instance can potentially trigger an RMP fault: thread A, sev_gmem_post_populate: called thread B, sev_gmem_prepare: places below 'pfn' in a private state in RMP thread A, sev_gmem_post_populate: *vaddr = kmap_local_pfn(pfn + i); thread A, sev_gmem_post_populate: copy_from_user(vaddr, src + i * PAGE_SIZE, PAGE_SIZE); RMP #PF Fix this by only allowing KVM_PRE_FAULT_MEMORY to run after a guest's initial private memory contents have been finalized via KVM_SEV_SNP_LAUNCH_FINISH. Beyond fixing this issue, it just sort of makes sense to enforce this, since the KVM_PRE_FAULT_MEMORY documentation states: "KVM maps memory as if the vCPU generated a stage-2 read page fault" which sort of implies we should be acting on the same guest state that a vCPU would see post-launch after the initial guest memory is all set up. Co-developed-by: Michael Roth <michael.roth@amd.com> Signed-off-by: Michael Roth <michael.roth@amd.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
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| ABI | ||
| accel | ||
| accounting | ||
| admin-guide | ||
| arch | ||
| block | ||
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| cdrom | ||
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| w1 | ||
| watchdog | ||
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| .gitignore | ||
| atomic_bitops.txt | ||
| atomic_t.txt | ||
| Changes | ||
| CodingStyle | ||
| conf.py | ||
| docutils.conf | ||
| dontdiff | ||
| index.rst | ||
| Kconfig | ||
| Makefile | ||
| memory-barriers.txt | ||
| SubmittingPatches | ||
| subsystem-apis.rst | ||