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KVM: arm/arm64: vgic-v3: Use PREbits to infer the number of ICH_APxRn_EL2 registers 

The GICv3 documentation is extremely confusing, as it talks about
the number of priorities represented by the ICH_APxRn_EL2 registers,
while it should really talk about the number of preemption levels.

This leads to a bug where we may access undefined ICH_APxRn_EL2
registers, since PREbits is allowed to be smaller than PRIbits.
Thankfully, nobody seem to have taken this path so far...

The fix is to use ICH_VTR_EL2.PREbits instead.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
This commit is contained in:
Marc Zyngier 2017-05-02 14:30:41 +01:00 committed by Christoffer Dall
parent 3d6e77ad14
commit 15d2bffdde
1 changed files with 9 additions and 9 deletions
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18
virt/kvm/arm/hyp/vgic-v3-sr.c
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@ -22,7 +22,7 @@
#include <asm/kvm_hyp.h> #include <asm/kvm_hyp.h>
#define vtr_to_max_lr_idx(v) ((v) & 0xf) #define vtr_to_max_lr_idx(v) ((v) & 0xf)
#define vtr_to_nr_pri_bits(v) (((u32)(v) >> 29) + 1) #define vtr_to_nr_pre_bits(v) (((u32)(v) >> 26) + 1)
static u64 __hyp_text __gic_v3_get_lr(unsigned int lr) static u64 __hyp_text __gic_v3_get_lr(unsigned int lr)
{ {
@ -135,13 +135,13 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
if (used_lrs) { if (used_lrs) {
int i; int i;
u32 nr_pri_bits; u32 nr_pre_bits;
cpu_if->vgic_elrsr = read_gicreg(ICH_ELSR_EL2); cpu_if->vgic_elrsr = read_gicreg(ICH_ELSR_EL2);
write_gicreg(0, ICH_HCR_EL2); write_gicreg(0, ICH_HCR_EL2);
val = read_gicreg(ICH_VTR_EL2); val = read_gicreg(ICH_VTR_EL2);
nr_pri_bits = vtr_to_nr_pri_bits(val); nr_pre_bits = vtr_to_nr_pre_bits(val);
for (i = 0; i < used_lrs; i++) { for (i = 0; i < used_lrs; i++) {
if (cpu_if->vgic_elrsr & (1 << i)) if (cpu_if->vgic_elrsr & (1 << i))
@ -152,7 +152,7 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
__gic_v3_set_lr(0, i); __gic_v3_set_lr(0, i);
} }
switch (nr_pri_bits) { switch (nr_pre_bits) {
case 7: case 7:
cpu_if->vgic_ap0r[3] = read_gicreg(ICH_AP0R3_EL2); cpu_if->vgic_ap0r[3] = read_gicreg(ICH_AP0R3_EL2);
cpu_if->vgic_ap0r[2] = read_gicreg(ICH_AP0R2_EL2); cpu_if->vgic_ap0r[2] = read_gicreg(ICH_AP0R2_EL2);
@ -162,7 +162,7 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
cpu_if->vgic_ap0r[0] = read_gicreg(ICH_AP0R0_EL2); cpu_if->vgic_ap0r[0] = read_gicreg(ICH_AP0R0_EL2);
} }
switch (nr_pri_bits) { switch (nr_pre_bits) {
case 7: case 7:
cpu_if->vgic_ap1r[3] = read_gicreg(ICH_AP1R3_EL2); cpu_if->vgic_ap1r[3] = read_gicreg(ICH_AP1R3_EL2);
cpu_if->vgic_ap1r[2] = read_gicreg(ICH_AP1R2_EL2); cpu_if->vgic_ap1r[2] = read_gicreg(ICH_AP1R2_EL2);
@ -198,7 +198,7 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu)
struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3; struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs; u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
u64 val; u64 val;
u32 nr_pri_bits; u32 nr_pre_bits;
int i; int i;
/* /*
@ -217,12 +217,12 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu)
} }
val = read_gicreg(ICH_VTR_EL2); val = read_gicreg(ICH_VTR_EL2);
nr_pri_bits = vtr_to_nr_pri_bits(val); nr_pre_bits = vtr_to_nr_pre_bits(val);
if (used_lrs) { if (used_lrs) {
write_gicreg(cpu_if->vgic_hcr, ICH_HCR_EL2); write_gicreg(cpu_if->vgic_hcr, ICH_HCR_EL2);
switch (nr_pri_bits) { switch (nr_pre_bits) {
case 7: case 7:
write_gicreg(cpu_if->vgic_ap0r[3], ICH_AP0R3_EL2); write_gicreg(cpu_if->vgic_ap0r[3], ICH_AP0R3_EL2);
write_gicreg(cpu_if->vgic_ap0r[2], ICH_AP0R2_EL2); write_gicreg(cpu_if->vgic_ap0r[2], ICH_AP0R2_EL2);
@ -232,7 +232,7 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu)
write_gicreg(cpu_if->vgic_ap0r[0], ICH_AP0R0_EL2); write_gicreg(cpu_if->vgic_ap0r[0], ICH_AP0R0_EL2);
} }
switch (nr_pri_bits) { switch (nr_pre_bits) {
case 7: case 7:
write_gicreg(cpu_if->vgic_ap1r[3], ICH_AP1R3_EL2); write_gicreg(cpu_if->vgic_ap1r[3], ICH_AP1R3_EL2);
write_gicreg(cpu_if->vgic_ap1r[2], ICH_AP1R2_EL2); write_gicreg(cpu_if->vgic_ap1r[2], ICH_AP1R2_EL2);