tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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KVM: arm64: Eagerly init vgic dist/redist on vgic creation

If vgic_allocate_private_irqs_locked() fails for any odd reason,
we exit kvm_vgic_create() early, leaving dist->rd_regions uninitialised.

kvm_vgic_dist_destroy() then comes along and walks into the weeds
trying to free the RDs. Got to love this stuff.

Solve it by moving all the static initialisation early, and make
sure that if we fail halfway, we're in a reasonable shape to
perform the rest of the teardown. While at it, reset the vgic model
on failure, just in case...

Reported-by: syzbot+f6a46b038fc243ac0175@syzkaller.appspotmail.com
Tested-by: syzbot+f6a46b038fc243ac0175@syzkaller.appspotmail.com
Fixes: b3aa9283c0c50 ("KVM: arm64: vgic: Hoist SGI/PPI alloc from vgic_init() to kvm_create_vgic()")
Link: https://lore.kernel.org/r/69a2d58c.050a0220.3a55be.003b.GAE@google.com
Link: https://patch.msgid.link/20260228164559.936268-1-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org

Marc Zyngier ac6769c8 11439c46

+17 -17
+17 -17
arch/arm64/kvm/vgic/vgic-init.c
··· 143 143 kvm->arch.vgic.in_kernel = true; 144 144 kvm->arch.vgic.vgic_model = type; 145 145 kvm->arch.vgic.implementation_rev = KVM_VGIC_IMP_REV_LATEST; 146 - 147 - kvm_for_each_vcpu(i, vcpu, kvm) { 148 - ret = vgic_allocate_private_irqs_locked(vcpu, type); 149 - if (ret) 150 - break; 151 - } 152 - 153 - if (ret) { 154 - kvm_for_each_vcpu(i, vcpu, kvm) { 155 - struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu; 156 - kfree(vgic_cpu->private_irqs); 157 - vgic_cpu->private_irqs = NULL; 158 - } 159 - 160 - goto out_unlock; 161 - } 162 - 163 146 kvm->arch.vgic.vgic_dist_base = VGIC_ADDR_UNDEF; 164 147 165 148 aa64pfr0 = kvm_read_vm_id_reg(kvm, SYS_ID_AA64PFR0_EL1) & ~ID_AA64PFR0_EL1_GIC; ··· 158 175 159 176 kvm_set_vm_id_reg(kvm, SYS_ID_AA64PFR0_EL1, aa64pfr0); 160 177 kvm_set_vm_id_reg(kvm, SYS_ID_PFR1_EL1, pfr1); 178 + 179 + kvm_for_each_vcpu(i, vcpu, kvm) { 180 + ret = vgic_allocate_private_irqs_locked(vcpu, type); 181 + if (ret) 182 + break; 183 + } 184 + 185 + if (ret) { 186 + kvm_for_each_vcpu(i, vcpu, kvm) { 187 + struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu; 188 + kfree(vgic_cpu->private_irqs); 189 + vgic_cpu->private_irqs = NULL; 190 + } 191 + 192 + kvm->arch.vgic.vgic_model = 0; 193 + goto out_unlock; 194 + } 161 195 162 196 if (type == KVM_DEV_TYPE_ARM_VGIC_V3) 163 197 kvm->arch.vgic.nassgicap = system_supports_direct_sgis();