In order to be able to make S2 TLB invalidations more performant on NV, let's use a scheme derived from the FEAT_TTL extension. If bits [56:55] in the leaf descriptor translating the address in the corresponding shadow S2 are non-zero, they indicate a level which can be used as an invalidation range. This allows further reduction of the systematic over-invalidation that takes place otherwise. Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> --- arch/arm64/kvm/nested.c | 83 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 82 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index 8570b5bd0289..5ab5c43c571b 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -4,6 +4,7 @@ * Author: Jintack Lim <jintack.lim@xxxxxxxxxx> */ +#include <linux/bitfield.h> #include <linux/kvm.h> #include <linux/kvm_host.h> @@ -421,12 +422,92 @@ static unsigned int ttl_to_size(u8 ttl) return max_size; } +/* + * Compute the equivalent of the TTL field by parsing the shadow PT. The + * granule size is extracted from the cached VTCR_EL2.TG0 while the level is + * retrieved from first entry carrying the level as a tag. + */ +static u8 get_guest_mapping_ttl(struct kvm_s2_mmu *mmu, u64 addr) +{ + u64 tmp, sz = 0, vtcr = mmu->tlb_vtcr; + kvm_pte_t pte; + u8 ttl, level; + + switch (vtcr & VTCR_EL2_TG0_MASK) { + case VTCR_EL2_TG0_4K: + ttl = (TLBI_TTL_TG_4K << 2); + break; + case VTCR_EL2_TG0_16K: + ttl = (TLBI_TTL_TG_16K << 2); + break; + case VTCR_EL2_TG0_64K: + default: /* IMPDEF: treat any other value as 64k */ + ttl = (TLBI_TTL_TG_64K << 2); + break; + } + + tmp = addr; + +again: + /* Iteratively compute the block sizes for a particular granule size */ + switch (vtcr & VTCR_EL2_TG0_MASK) { + case VTCR_EL2_TG0_4K: + if (sz < SZ_4K) sz = SZ_4K; + else if (sz < SZ_2M) sz = SZ_2M; + else if (sz < SZ_1G) sz = SZ_1G; + else sz = 0; + break; + case VTCR_EL2_TG0_16K: + if (sz < SZ_16K) sz = SZ_16K; + else if (sz < SZ_32M) sz = SZ_32M; + else sz = 0; + break; + case VTCR_EL2_TG0_64K: + default: /* IMPDEF: treat any other value as 64k */ + if (sz < SZ_64K) sz = SZ_64K; + else if (sz < SZ_512M) sz = SZ_512M; + else sz = 0; + break; + } + + if (sz == 0) + return 0; + + tmp &= ~(sz - 1); + if (kvm_pgtable_get_leaf(mmu->pgt, tmp, &pte, NULL)) + goto again; + if (!(pte & PTE_VALID)) + goto again; + level = FIELD_GET(KVM_NV_GUEST_MAP_SZ, pte); + if (!level) + goto again; + + ttl |= level; + + /* + * We now have found some level information in the shadow S2. Check + * that the resulting range is actually including the original IPA. + */ + sz = ttl_to_size(ttl); + if (addr < (tmp + sz)) + return ttl; + + return 0; +} + unsigned long compute_tlb_inval_range(struct kvm_s2_mmu *mmu, u64 val) { + struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu); unsigned long max_size; u8 ttl; - ttl = FIELD_GET(GENMASK_ULL(47, 44), val); + ttl = FIELD_GET(TLBI_TTL_MASK, val); + + if (!ttl || !kvm_has_feat(kvm, ID_AA64MMFR2_EL1, TTL, IMP)) { + /* No TTL, check the shadow S2 for a hint */ + u64 addr = (val & GENMASK_ULL(35, 0)) << 12; + ttl = get_guest_mapping_ttl(mmu, addr); + } max_size = ttl_to_size(ttl); -- 2.39.2