Re: [RFC PATCH 09/28] arm64: RME: RTT handling

Ganapatrao Kulkarni
2024-03-18T11:01:49Z

On 27-01-2023 04:59 pm, Steven Price wrote:
> The RMM owns the stage 2 page tables for a realm, and KVM must request
> that the RMM creates/destroys entries as necessary. The physical pages
> to store the page tables are delegated to the realm as required, and can
> be undelegated when no longer used.
>
> Signed-off-by: Steven Price <steven.price@arm.com>
> ---
> arch/arm64/include/asm/kvm_rme.h | 19 +++++
> arch/arm64/kvm/mmu.c | 7 +-
> arch/arm64/kvm/rme.c | 139 +++++++++++++++++++++++++++++++
> 3 files changed, 162 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_rme.h b/arch/arm64/include/asm/kvm_rme.h
> index a6318af3ed11..eea5118dfa8a 100644
> --- a/arch/arm64/include/asm/kvm_rme.h
> +++ b/arch/arm64/include/asm/kvm_rme.h
> @@ -35,5 +35,24 @@ u32 kvm_realm_ipa_limit(void);
> int kvm_realm_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap);
> int kvm_init_realm_vm(struct kvm *kvm);
> void kvm_destroy_realm(struct kvm *kvm);
> +void kvm_realm_destroy_rtts(struct realm *realm, u32 ia_bits, u32 start_level);
> +
> +#define RME_RTT_BLOCK_LEVEL 2
> +#define RME_RTT_MAX_LEVEL 3
> +
> +#define RME_PAGE_SHIFT 12
> +#define RME_PAGE_SIZE BIT(RME_PAGE_SHIFT)

Can we use PAGE_SIZE and PAGE_SHIFT instead of redefining?
May be we can use them to define RME_PAGE_SIZE and RME_PAGE_SHIFT.

> +/* See ARM64_HW_PGTABLE_LEVEL_SHIFT() */
> +#define RME_RTT_LEVEL_SHIFT(l) \
> + ((RME_PAGE_SHIFT - 3) * (4 - (l)) + 3)

Instead of defining again, can we define to
ARM64_HW_PGTABLE_LEVEL_SHIFT?

> +#define RME_L2_BLOCK_SIZE BIT(RME_RTT_LEVEL_SHIFT(2))
> +
> +static inline unsigned long rme_rtt_level_mapsize(int level)
> +{
> + if (WARN_ON(level > RME_RTT_MAX_LEVEL))
> + return RME_PAGE_SIZE;
> +
> + return (1UL << RME_RTT_LEVEL_SHIFT(level));
> +}
>
> #endif
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 22c00274884a..f29558c5dcbc 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -834,16 +834,17 @@ void stage2_unmap_vm(struct kvm *kvm)
> void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu)
> {
> struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu);
> - struct kvm_pgtable *pgt = NULL;
> + struct kvm_pgtable *pgt;
>
> write_lock(&kvm->mmu_lock);
> + pgt = mmu->pgt;
> if (kvm_is_realm(kvm) &&
> kvm_realm_state(kvm) != REALM_STATE_DYING) {
> - /* TODO: teardown rtts */
> write_unlock(&kvm->mmu_lock);
> + kvm_realm_destroy_rtts(&kvm->arch.realm, pgt->ia_bits,
> + pgt->start_level);
> return;
> }
> - pgt = mmu->pgt;
> if (pgt) {
> mmu->pgd_phys = 0;
> mmu->pgt = NULL;
> diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c
> index 0c9d70e4d9e6..f7b0e5a779f8 100644
> --- a/arch/arm64/kvm/rme.c
> +++ b/arch/arm64/kvm/rme.c
> @@ -73,6 +73,28 @@ static int rmi_check_version(void)
> return 0;
> }
>
> +static void realm_destroy_undelegate_range(struct realm *realm,
> + unsigned long ipa,
> + unsigned long addr,
> + ssize_t size)
> +{
> + unsigned long rd = virt_to_phys(realm->rd);
> + int ret;
> +
> + while (size > 0) {
> + ret = rmi_data_destroy(rd, ipa);
> + WARN_ON(ret);
> + ret = rmi_granule_undelegate(addr);
> +
> + if (ret)
> + get_page(phys_to_page(addr));
> +
> + addr += PAGE_SIZE;
> + ipa += PAGE_SIZE;
> + size -= PAGE_SIZE;
> + }
> +}
> +
> static unsigned long create_realm_feat_reg0(struct kvm *kvm)
> {
> unsigned long ia_bits = VTCR_EL2_IPA(kvm->arch.vtcr);
> @@ -170,6 +192,123 @@ static int realm_create_rd(struct kvm *kvm)
> return r;
> }
>
> +static int realm_rtt_destroy(struct realm *realm, unsigned long addr,
> + int level, phys_addr_t rtt_granule)
> +{
> + addr = ALIGN_DOWN(addr, rme_rtt_level_mapsize(level - 1));
> + return rmi_rtt_destroy(rtt_granule, virt_to_phys(realm->rd), addr,
> + level);
> +}
> +
> +static int realm_destroy_free_rtt(struct realm *realm, unsigned long addr,
> + int level, phys_addr_t rtt_granule)
> +{
> + if (realm_rtt_destroy(realm, addr, level, rtt_granule))
> + return -ENXIO;
> + if (!WARN_ON(rmi_granule_undelegate(rtt_granule)))
> + put_page(phys_to_page(rtt_granule));
> +
> + return 0;
> +}
> +
> +static int realm_rtt_create(struct realm *realm,
> + unsigned long addr,
> + int level,
> + phys_addr_t phys)
> +{
> + addr = ALIGN_DOWN(addr, rme_rtt_level_mapsize(level - 1));
> + return rmi_rtt_create(phys, virt_to_phys(realm->rd), addr, level);
> +}
> +
> +static int realm_tear_down_rtt_range(struct realm *realm, int level,
> + unsigned long start, unsigned long end)
> +{
> + phys_addr_t rd = virt_to_phys(realm->rd);
> + ssize_t map_size = rme_rtt_level_mapsize(level);
> + unsigned long addr, next_addr;
> + bool failed = false;
> +
> + for (addr = start; addr < end; addr = next_addr) {
> + phys_addr_t rtt_addr, tmp_rtt;
> + struct rtt_entry rtt;
> + unsigned long end_addr;
> +
> + next_addr = ALIGN(addr + 1, map_size);
> +
> + end_addr = min(next_addr, end);
> +
> + if (rmi_rtt_read_entry(rd, ALIGN_DOWN(addr, map_size),
> + level, &rtt)) {
> + failed = true;
> + continue;
> + }
> +
> + rtt_addr = rmi_rtt_get_phys(&rtt);
> + WARN_ON(level != rtt.walk_level);
> +
> + switch (rtt.state) {
> + case RMI_UNASSIGNED:
> + case RMI_DESTROYED:
> + break;
> + case RMI_TABLE:
> + if (realm_tear_down_rtt_range(realm, level + 1,
> + addr, end_addr)) {
> + failed = true;
> + break;
> + }
> + if (IS_ALIGNED(addr, map_size) &&
> + next_addr <= end &&
> + realm_destroy_free_rtt(realm, addr, level + 1,
> + rtt_addr))
> + failed = true;
> + break;
> + case RMI_ASSIGNED:
> + WARN_ON(!rtt_addr);
> + /*
> + * If there is a block mapping, break it now, using the
> + * spare_page. We are sure to have a valid delegated
> + * page at spare_page before we enter here, otherwise
> + * WARN once, which will be followed by further
> + * warnings.
> + */
> + tmp_rtt = realm->spare_page;
> + if (level == 2 &&
> + !WARN_ON_ONCE(tmp_rtt == PHYS_ADDR_MAX) &&
> + realm_rtt_create(realm, addr,
> + RME_RTT_MAX_LEVEL, tmp_rtt)) {
> + WARN_ON(1);
> + failed = true;
> + break;
> + }
> + realm_destroy_undelegate_range(realm, addr,
> + rtt_addr, map_size);
> + /*
> + * Collapse the last level table and make the spare page
> + * reusable again.
> + */
> + if (level == 2 &&
> + realm_rtt_destroy(realm, addr, RME_RTT_MAX_LEVEL,
> + tmp_rtt))
> + failed = true;
> + break;
> + case RMI_VALID_NS:
> + WARN_ON(rmi_rtt_unmap_unprotected(rd, addr, level));
> + break;
> + default:
> + WARN_ON(1);
> + failed = true;
> + break;
> + }
> + }
> +
> + return failed ? -EINVAL : 0;
> +}
> +
> +void kvm_realm_destroy_rtts(struct realm *realm, u32 ia_bits, u32 start_level)
> +{
> + realm_tear_down_rtt_range(realm, start_level, 0, (1UL << ia_bits));
> +}
> +
> /* Protects access to rme_vmid_bitmap */
> static DEFINE_SPINLOCK(rme_vmid_lock);
> static unsigned long *rme_vmid_bitmap;

Thanks,
Ganapat