[PATCH v2 6/8] KVM: arm64: Sign-extend VA for range-based TLBI invalidation

[Marc Zyngier <maz@kernel.org>]

When the decode_range_tlbi() helper was moved to be used for S1 TLBIs,
the required sign extension was omitted. Add it.

As a result, special care must be taken to not overflow PA bits when
this is used for S2 invalidation.

Fixes: 85bba00425ae0 ("KVM: arm64: nv: Move TLBI range decoding to a helper")
Reported-by: sashiko-bot@kernel.org
Link: https://lore.kernel.org/r/20260801130337.EB2BA1F00AC4@smtp.kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
---
 arch/arm64/include/asm/kvm_nested.h |  7 +++++++
 arch/arm64/kvm/sys_regs.c           | 11 +++++++++++
 2 files changed, 18 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h
index bfed664d823bd..c83be6d0e79ac 100644
--- a/arch/arm64/include/asm/kvm_nested.h
+++ b/arch/arm64/include/asm/kvm_nested.h
@@ -291,6 +291,13 @@ static inline u64 decode_range_tlbi(u64 val, u64 *range, u16 *asid)
 
 	base	= (val & GENMASK(36, 0)) << shift;
 
+	/*
+	 * We only deal with at most 48bit VA/IPA, so 48 is where we
+	 * sign-extend from. Should we support FEAT_L{VP}A* at some point,
+	 * this will need to be revisited.
+	 */
+	base	= (u64)sign_extend64(base, 48);
+
 	if (asid)
 		*asid = FIELD_GET(TLBIR_ASID_MASK, val);
 
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 5d5c579d45790..797e888bf9394 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -4057,6 +4057,7 @@ static bool handle_ripas2e1is(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 	u32 sys_encoding = sys_insn(p->Op0, p->Op1, p->CRn, p->CRm, p->Op2);
 	u64 vttbr = vcpu_read_sys_reg(vcpu, VTTBR_EL2);
 	u64 base, range;
+	int pa_bits;
 
 	if (!kvm_supported_tlbi_ipas2_op(vcpu, sys_encoding))
 		return undef_access(vcpu, p, r);
@@ -4068,6 +4069,16 @@ static bool handle_ripas2e1is(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 	 */
 	base = decode_range_tlbi(p->regval, &range, NULL);
 
+	/*
+	 * Ignore TLBIs that start out of PA_bits range, and cap the
+	 * invalidation to the [base:bit(PA_bits)] interval.
+	 */
+	pa_bits = kvm_get_pa_bits(vcpu->kvm);
+	if (fls64(base) > pa_bits)
+		return true;
+
+	range = min(range, BIT_ULL(pa_bits) - base);
+
 	kvm_s2_mmu_iterate_by_vmid(vcpu->kvm, get_vmid(vttbr),
 				   &(union tlbi_info) {
 					   .range = {
-- 
2.47.3