On Mon, 20 Feb 2023 12:38:41 -0600
Michael Roth <michael.roth@xxxxxxx> wrote:
> Implement a platform hook to do the work of restoring the direct map
> entries and cleaning up RMP table entries for restricted memory that is
> being freed back to the host.
>
> Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
> ---
> arch/x86/kvm/svm/sev.c | 62 ++++++++++++++++++++++++++++++++++++++++++
> arch/x86/kvm/svm/svm.c | 1 +
> arch/x86/kvm/svm/svm.h | 1 +
> 3 files changed, 64 insertions(+)
>
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 7a74a92cb39a..bedec90d034f 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -4509,3 +4509,65 @@ bool sev_fault_is_private(struct kvm *kvm, gpa_t gpa, u64 error_code, bool *priv
>
> return true;
> }
> +
> +void sev_invalidate_private_range(struct kvm_memory_slot *slot, gfn_t start, gfn_t end)
> +{
> + gfn_t gfn = start;
> +
> + if (!sev_snp_guest(slot->kvm))
> + return;
> +
> + if (!kvm_slot_can_be_private(slot)) {
> + pr_warn_ratelimited("SEV: Memslot for GFN: 0x%llx is not private.\n",
> + gfn);
> + return;
> + }
> +
This is a generic check for both SNP and TDX, it should be moved to
kvm_restrictedmem_invalidate_begin().
> + while (gfn <= end) {
> + gpa_t gpa = gfn_to_gpa(gfn);
> + int level = PG_LEVEL_4K;
> + int order, rc;
> + kvm_pfn_t pfn;
> +
> + rc = kvm_restrictedmem_get_pfn(slot, gfn, &pfn, &order);
> + if (rc) {
> + pr_warn_ratelimited("SEV: Failed to retrieve restricted PFN for GFN 0x%llx, rc: %d\n",
> + gfn, rc);
> + gfn++;
> + continue;
> + }
> +
> + if (order) {
> + int rmp_level;
> +
> + if (IS_ALIGNED(gpa, page_level_size(PG_LEVEL_2M)) &&
> + gpa + page_level_size(PG_LEVEL_2M) <= gfn_to_gpa(end))
> + level = PG_LEVEL_2M;
> + else
> + pr_debug("%s: GPA 0x%llx is not aligned to 2M, skipping 2M directmap restoration\n",
> + __func__, gpa);
> +
> + /*
> + * TODO: It may still be possible to restore 2M mapping here,
> + * but keep it simple for now.
> + */
> + if (level == PG_LEVEL_2M &&
> + (!snp_lookup_rmpentry(pfn, &rmp_level) || rmp_level == PG_LEVEL_4K)) {
> + pr_debug("%s: PFN 0x%llx is not mapped as 2M private range, skipping 2M directmap restoration\n",
> + __func__, pfn);
> + level = PG_LEVEL_4K;
> + }
> + }
> +
> + pr_debug("%s: GPA %llx PFN %llx order %d level %d\n",
> + __func__, gpa, pfn, order, level);
> + rc = snp_make_page_shared(slot->kvm, gpa, pfn, level);
> + if (rc)
> + pr_err("SEV: Failed to restore page to shared, GPA: 0x%llx PFN: 0x%llx order: %d rc: %d\n",
> + gpa, pfn, order, rc);
> +
> + gfn += page_level_size(level) >> PAGE_SHIFT;
> + put_page(pfn_to_page(pfn));
> + cond_resched();
> + }
> +}
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 18e4a6c17d11..3fe5f13b5f3a 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -4862,6 +4862,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
> .adjust_mapping_level = sev_adjust_mapping_level,
> .update_mem_attr = sev_update_mem_attr,
> .fault_is_private = sev_fault_is_private,
> + .invalidate_restricted_mem = sev_invalidate_private_range,
> };
>
> /*
> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index 97038afa8020..857b674e68f0 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -727,6 +727,7 @@ void handle_rmp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code);
> void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu);
> int sev_update_mem_attr(struct kvm_memory_slot *slot, unsigned int attr,
> gfn_t start, gfn_t end);
> +void sev_invalidate_private_range(struct kvm_memory_slot *slot, gfn_t start, gfn_t end);
>
> bool sev_fault_is_private(struct kvm *kvm, gpa_t gpa, u64 error_code, bool *private_fault);
>
