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charset="utf-8" Commit 7e066cb9b71a ("KVM: SEV: Use long-term pin when registering encrypted memory regions") added FOLL_LONGTERM to sev_mem_enc_register_region() so anonymous guest RAM is migrated out of MIGRATE_CMA/ZONE_MOVABLE before a long term pin. It also kept FOLL_WRITE on the pin. Combining FOLL_WRITE with FOLL_LONGTERM breaks registration of file-backed guest memory, such as virtio-pmem host memory-backend-file mappings (MAP_SHARED). GUP rejects long-term writable pins on dirty tracked file mappings since: commit 8ac268436e6d ("mm/gup: disallow FOLL_LONGTERM GUP-nonfast writing to= file-backed mappings") commit a6e79df92e4a ("mm/gup: disallow FOLL_LONGTERM GUP-fast writing to fi= le-backed mappings"). Region registration only requires long-term pin to prevent page migration a= nd does not write through this GUP pin. Drop FOLL_WRITE and pin guest memory only with FOLL_LONGTERM. Fixes: 7e066cb9b71a ("KVM: SEV: Use long-term pin when registering encrypte= d memory regions") Cc: stable@vger.kernel.org Suggested-by: "David Hildenbrand (Arm)" Link: https://lore.kernel.org/all/ad784f05-b36c-4e91-9f17-4c5b826735d0@kern= el.org/ Signed-off-by: Pankaj Gupta Acked-by: David Hildenbrand (Arm) Acked-by: Lorenzo Stoakes (ARM) --- v1 -> v2 - Remove FOLL_WRITE when the pin is not used for host writes v1: https://lore.kernel.org/all/20260701144543.39582-1-pankaj.gupta@amd.com/ arch/x86/kvm/svm/sev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 427229347876..5f2998761462 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2752,7 +2752,7 @@ int sev_mem_enc_register_region(struct kvm *kvm, return -ENOMEM; =20 region->pages =3D sev_pin_memory(kvm, range->addr, range->size, ®ion->= npages, - FOLL_WRITE | FOLL_LONGTERM); + FOLL_LONGTERM); if (IS_ERR(region->pages)) { ret =3D PTR_ERR(region->pages); goto e_free; --=20 2.34.1