[PATCH 05/12] KVM: arm64: Add helper for last ditch idreg adjustments

Marc Zyngier
2024-08-20T10:06:13Z

We already have to perform a set of last-chance adjustments for
NV purposes. We will soon have to do the same for the GIC, so
introduce a helper for that exact purpose.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/kvm/arm.c | 10 +++++-----
arch/arm64/kvm/nested.c | 15 +++++----------
arch/arm64/kvm/sys_regs.c | 23 +++++++++++++++++++++++
arch/arm64/kvm/sys_regs.h | 2 ++
4 files changed, 35 insertions(+), 15 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 9bef7638342e..fc46457d38d6 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -46,6 +46,8 @@
#include <kvm/arm_pmu.h>
#include <kvm/arm_psci.h>

+#include "sys_regs.h"
+
static enum kvm_mode kvm_mode = KVM_MODE_DEFAULT;

enum kvm_wfx_trap_policy {
@@ -821,11 +823,9 @@ int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu)
return ret;
}

- if (vcpu_has_nv(vcpu)) {
- ret = kvm_init_nv_sysregs(vcpu->kvm);
- if (ret)
- return ret;
- }
+ ret = kvm_finalize_sys_regs(vcpu);
+ if (ret)
+ return ret;

/*
* This needs to happen after NV has imposed its own restrictions on
diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
index bab27f9d8cc6..e2067c594e4a 100644
--- a/arch/arm64/kvm/nested.c
+++ b/arch/arm64/kvm/nested.c
@@ -954,19 +954,16 @@ static void set_sysreg_masks(struct kvm *kvm, int sr, u64 res0, u64 res1)
int kvm_init_nv_sysregs(struct kvm *kvm)
{
u64 res0, res1;
- int ret = 0;

- mutex_lock(&kvm->arch.config_lock);
+ lockdep_assert_held(&kvm->arch.config_lock);

if (kvm->arch.sysreg_masks)
- goto out;
+ return 0;

kvm->arch.sysreg_masks = kzalloc(sizeof(*(kvm->arch.sysreg_masks)),
GFP_KERNEL_ACCOUNT);
- if (!kvm->arch.sysreg_masks) {
- ret = -ENOMEM;
- goto out;
- }
+ if (!kvm->arch.sysreg_masks)
+ return -ENOMEM;

limit_nv_id_regs(kvm);

@@ -1195,8 +1192,6 @@ int kvm_init_nv_sysregs(struct kvm *kvm)
if (!kvm_has_feat(kvm, ID_AA64PFR0_EL1, AMU, V1P1))
res0 |= ~(res0 | res1);
set_sysreg_masks(kvm, HAFGRTR_EL2, res0, res1);
-out:
- mutex_unlock(&kvm->arch.config_lock);

- return ret;
+ return 0;
}
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 257c8da23a4e..bc2d54da3827 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -4620,6 +4620,29 @@ void kvm_calculate_traps(struct kvm_vcpu *vcpu)
mutex_unlock(&kvm->arch.config_lock);
}

+/*
+ * Perform last adjustments to the ID registers that are implied by the
+ * configuration outside of the ID regs themselves, as well as any
+ * initialisation that directly depend on these ID registers (such as
+ * RES0/RES1 behaviours). This is not the place to configure traps though.
+ *
+ * Because this can be called once per CPU, changes must be idempotent.
+ */
+int kvm_finalize_sys_regs(struct kvm_vcpu *vcpu)
+{
+ struct kvm *kvm = vcpu->kvm;
+
+ guard(mutex)(&kvm->arch.config_lock);
+
+ if (vcpu_has_nv(vcpu)) {
+ int ret = kvm_init_nv_sysregs(kvm);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
int __init kvm_sys_reg_table_init(void)
{
bool valid = true;
diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h
index 997eea21ba2a..7c9b4eb0baa6 100644
--- a/arch/arm64/kvm/sys_regs.h
+++ b/arch/arm64/kvm/sys_regs.h
@@ -235,6 +235,8 @@ int kvm_sys_reg_set_user(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg,

bool triage_sysreg_trap(struct kvm_vcpu *vcpu, int *sr_index);

+int kvm_finalize_sys_regs(struct kvm_vcpu *vcpu);
+
#define AA32(_x) .aarch32_map = AA32_##_x
#define Op0(_x) .Op0 = _x
#define Op1(_x) .Op1 = _x
--
2.39.2