From e4ee5447927377c55777b73fe497a2455a25f948 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 11 Jul 2024 18:27:55 -0400 Subject: [PATCH] KVM: guest_memfd: let kvm_gmem_populate() operate only on private gfns This check is currently performed by sev_gmem_post_populate(), but it applies to all callers of kvm_gmem_populate(): the point of the function is that the memory is being encrypted and some work has to be done on all the gfns in order to encrypt them. Therefore, check the KVM_MEMORY_ATTRIBUTE_PRIVATE attribute prior to invoking the callback, and stop the operation if a shared page is encountered. Because CONFIG_KVM_PRIVATE_MEM in principle does not require attributes, this makes kvm_gmem_populate() depend on CONFIG_KVM_GENERIC_PRIVATE_MEM (which does require them). Reviewed-by: Michael Roth Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/sev.c | 7 ------- include/linux/kvm_host.h | 2 ++ virt/kvm/guest_memfd.c | 12 ++++++++++++ 3 files changed, 14 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 752d2fff0f10..532df12b43c5 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2279,13 +2279,6 @@ static int sev_gmem_post_populate(struct kvm *kvm, gfn_t gfn_start, kvm_pfn_t pf bool assigned; int level; - if (!kvm_mem_is_private(kvm, gfn)) { - pr_debug("%s: Failed to ensure GFN 0x%llx has private memory attribute set\n", - __func__, gfn); - ret = -EINVAL; - goto err; - } - ret = snp_lookup_rmpentry((u64)pfn + i, &assigned, &level); if (ret || assigned) { pr_debug("%s: Failed to ensure GFN 0x%llx RMP entry is initial shared state, ret: %d assigned: %d\n", diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index c223b97df03e..79a6b1a63027 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -2449,6 +2449,7 @@ static inline int kvm_gmem_get_pfn(struct kvm *kvm, int kvm_arch_gmem_prepare(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, int max_order); #endif +#ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM /** * kvm_gmem_populate() - Populate/prepare a GPA range with guest data * @@ -2475,6 +2476,7 @@ typedef int (*kvm_gmem_populate_cb)(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, long kvm_gmem_populate(struct kvm *kvm, gfn_t gfn, void __user *src, long npages, kvm_gmem_populate_cb post_populate, void *opaque); +#endif #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE void kvm_arch_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end); diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 319ec491ca47..95e338a29910 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -612,6 +612,7 @@ out: } EXPORT_SYMBOL_GPL(kvm_gmem_get_pfn); +#ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, long npages, kvm_gmem_populate_cb post_populate, void *opaque) { @@ -665,11 +666,21 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, long (npages - i) < (1 << max_order)) max_order = 0; + ret = -EINVAL; + while (!kvm_range_has_memory_attributes(kvm, gfn, gfn + (1 << max_order), + KVM_MEMORY_ATTRIBUTE_PRIVATE, + KVM_MEMORY_ATTRIBUTE_PRIVATE)) { + if (!max_order) + goto put_folio_and_exit; + max_order--; + } + p = src ? src + i * PAGE_SIZE : NULL; ret = post_populate(kvm, gfn, pfn, p, max_order, opaque); if (!ret) folio_mark_uptodate(folio); +put_folio_and_exit: folio_put(folio); if (ret) break; @@ -681,3 +692,4 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, long return ret && !i ? ret : i; } EXPORT_SYMBOL_GPL(kvm_gmem_populate); +#endif