[PATCH 1/3] KVM: arm64: nv: Check S2 limits based on implemented PA size
From: Zenghui Yu <hidden>
Date: 2026-02-25 17:36:00
Also in:
kvmarm
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
From: "Zenghui Yu (Huawei)" <redacted>
check_base_s2_limits() checks the validity of SL0 and inputsize against
ia_size (inputsize again!) but the pseudocode from DDI0487 G.a
AArch64.TranslationTableWalk() says that we should check against the
implemented PA size.
We would otherwise fail to walk S2 with a valid configuration. E.g.,
granule size = 4KB, inputsize = 40 bits, initial lookup level = 0 (no
concatenation) on a system with 48 bits PA range supported is allowed by
architecture.
Fix it by obtaining PA size by kvm_get_pa_bits(). Note that
kvm_get_pa_bits() returns the fixed limit now and should eventually reflect
the per VM PARange (one day!). Given that the configured PARange should not
be greater that kvm_ipa_limit, it at least fixes the problem described
above.
While at it, inject a level 0 translation fault to guest if
check_base_s2_limits() fails, as per the pseudocode.
Fixes: 61e30b9eef7f ("KVM: arm64: nv: Implement nested Stage-2 page table walk logic")
Signed-off-by: Zenghui Yu (Huawei) <redacted>
---
arch/arm64/kvm/nested.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
index 620126d1f0dc..44ed3915b961 100644
--- a/arch/arm64/kvm/nested.c
+++ b/arch/arm64/kvm/nested.c@@ -152,31 +152,31 @@ static int get_ia_size(struct s2_walk_info *wi) return 64 - wi->t0sz; } -static int check_base_s2_limits(struct s2_walk_info *wi, +static int check_base_s2_limits(struct kvm_vcpu *vcpu, struct s2_walk_info *wi, int level, int input_size, int stride) { - int start_size, ia_size; + int start_size, pa_max; - ia_size = get_ia_size(wi); + pa_max = kvm_get_pa_bits(vcpu->kvm); /* Check translation limits */ switch (BIT(wi->pgshift)) { case SZ_64K: - if (level == 0 || (level == 1 && ia_size <= 42)) + if (level == 0 || (level == 1 && pa_max <= 42)) return -EFAULT; break; case SZ_16K: - if (level == 0 || (level == 1 && ia_size <= 40)) + if (level == 0 || (level == 1 && pa_max <= 40)) return -EFAULT; break; case SZ_4K: - if (level < 0 || (level == 0 && ia_size <= 42)) + if (level < 0 || (level == 0 && pa_max <= 42)) return -EFAULT; break; } /* Check input size limits */ - if (input_size > ia_size) + if (input_size > pa_max) return -EFAULT; /* Check number of entries in starting level table */
@@ -269,9 +269,11 @@ static int walk_nested_s2_pgd(struct kvm_vcpu *vcpu, phys_addr_t ipa, if (input_size > 48 || input_size < 25) return -EFAULT; - ret = check_base_s2_limits(wi, level, input_size, stride); - if (WARN_ON(ret)) + ret = check_base_s2_limits(vcpu, wi, level, input_size, stride); + if (WARN_ON(ret)) { + out->esr = compute_fsc(0, ESR_ELx_FSC_FAULT); return ret; + } base_lower_bound = 3 + input_size - ((3 - level) * stride + wi->pgshift);
--
2.53.0