Messages in this thread | | | Date | Wed, 17 Apr 2024 11:19:42 +0100 | Subject | Re: [PATCH v2 12/43] arm64: RME: Keep a spare page delegated to the RMM | From | Suzuki K Poulose <> |
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Hi Steven
On 12/04/2024 09:42, Steven Price wrote: > Pages can only be populated/destroyed on the RMM at the 4KB granule, > this requires creating the full depth of RTTs. However if the pages are > going to be combined into a 4MB huge page the last RTT is only
minor nit: 2MB huge page.
> temporarily needed. Similarly when freeing memory the huge page must be > temporarily split requiring temporary usage of the full depth oF RTTs. > > To avoid needing to perform a temporary allocation and delegation of a > page for this purpose we keep a spare delegated page around. In > particular this avoids the need for memory allocation while destroying > the realm guest. > > Signed-off-by: Steven Price <steven.price@arm.com> > --- > arch/arm64/include/asm/kvm_rme.h | 5 +++++ > arch/arm64/kvm/rme.c | 8 ++++++++ > 2 files changed, 13 insertions(+) > > diff --git a/arch/arm64/include/asm/kvm_rme.h b/arch/arm64/include/asm/kvm_rme.h > index cf8cc4d30364..fba85e9ce3ae 100644 > --- a/arch/arm64/include/asm/kvm_rme.h > +++ b/arch/arm64/include/asm/kvm_rme.h > @@ -50,6 +50,9 @@ enum realm_state { > * @state: The lifetime state machine for the realm > * @rd: Kernel mapping of the Realm Descriptor (RD) > * @params: Parameters for the RMI_REALM_CREATE command > + * @spare_page: A physical page that has been delegated to the Realm world but > + * is otherwise free. Used to avoid temporary allocation during > + * RTT operations. > * @num_aux: The number of auxiliary pages required by the RMM > * @vmid: VMID to be used by the RMM for the realm > * @ia_bits: Number of valid Input Address bits in the IPA > @@ -60,6 +63,8 @@ struct realm { > void *rd; > struct realm_params *params; > > + phys_addr_t spare_page; > + > unsigned long num_aux; > unsigned int vmid; > unsigned int ia_bits; > diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c > index 658d14e8d87d..9652ec6ab2fd 100644 > --- a/arch/arm64/kvm/rme.c > +++ b/arch/arm64/kvm/rme.c > @@ -103,6 +103,7 @@ static int realm_create_rd(struct kvm *kvm) > } > > realm->rd = rd; > + realm->spare_page = PHYS_ADDR_MAX; > > if (WARN_ON(rmi_rec_aux_count(rd_phys, &realm->num_aux))) { > WARN_ON(rmi_realm_destroy(rd_phys)); > @@ -283,6 +284,13 @@ void kvm_destroy_realm(struct kvm *kvm) > > rme_vmid_release(realm->vmid); > > + if (realm->spare_page != PHYS_ADDR_MAX) { > + /* Leak the page if the undelegate fails */ > + if (!WARN_ON(rmi_granule_undelegate(realm->spare_page))) > + free_page((unsigned long)phys_to_virt(realm->spare_page)); > + realm->spare_page = PHYS_ADDR_MAX; > + } > + > for (i = 0; i < pgt->pgd_pages; i++) { > phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i * PAGE_SIZE; >
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
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