[PATCH 8/8] KVM: arm64: Get rid of vCPU-scoped feature bitmap

Oliver Upton
2023-09-20T19:51:06Z

The vCPU-scoped feature bitmap was left in place a couple of releases
ago in case the change to VM-scoped vCPU features broke anyone. Nobody
has complained and the interop between VM and vCPU bitmaps is pretty
gross. Throw it out.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
arch/arm64/include/asm/kvm_emulate.h | 13 ++++++-------
arch/arm64/include/asm/kvm_host.h | 3 ---
arch/arm64/include/asm/kvm_nested.h | 3 ++-
arch/arm64/kvm/arm.c | 9 ++++-----
arch/arm64/kvm/hypercalls.c | 2 +-
arch/arm64/kvm/reset.c | 6 +++---
include/kvm/arm_pmu.h | 2 +-
include/kvm/arm_psci.h | 2 +-
8 files changed, 18 insertions(+), 22 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 3d6725ff0bf6..965b4cd8c247 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -54,6 +54,11 @@ void kvm_emulate_nested_eret(struct kvm_vcpu *vcpu);
int kvm_inject_nested_sync(struct kvm_vcpu *vcpu, u64 esr_el2);
int kvm_inject_nested_irq(struct kvm_vcpu *vcpu);

+static inline bool vcpu_has_feature(const struct kvm_vcpu *vcpu, int feature)
+{
+ return test_bit(feature, vcpu->kvm->arch.vcpu_features);
+}
+
#if defined(__KVM_VHE_HYPERVISOR__) || defined(__KVM_NVHE_HYPERVISOR__)
static __always_inline bool vcpu_el1_is_32bit(struct kvm_vcpu *vcpu)
{
@@ -62,7 +67,7 @@ static __always_inline bool vcpu_el1_is_32bit(struct kvm_vcpu *vcpu)
#else
static __always_inline bool vcpu_el1_is_32bit(struct kvm_vcpu *vcpu)
{
- return test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features);
+ return vcpu_has_feature(vcpu, KVM_ARM_VCPU_EL1_32BIT);
}
#endif

@@ -565,12 +570,6 @@ static __always_inline void kvm_incr_pc(struct kvm_vcpu *vcpu)
vcpu_set_flag((v), e); \
} while (0)

-
-static inline bool vcpu_has_feature(struct kvm_vcpu *vcpu, int feature)
-{
- return test_bit(feature, vcpu->arch.features);
-}
-
static __always_inline void kvm_write_cptr_el2(u64 val)
{
if (has_vhe() || has_hvhe())
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index cb2cde7b2682..c3a17888f183 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -574,9 +574,6 @@ struct kvm_vcpu_arch {
/* Cache some mmu pages needed inside spinlock regions */
struct kvm_mmu_memory_cache mmu_page_cache;

- /* feature flags */
- DECLARE_BITMAP(features, KVM_VCPU_MAX_FEATURES);
-
/* Virtual SError ESR to restore when HCR_EL2.VSE is set */
u64 vsesr_el2;

diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h
index fa23cc9c2adc..6cec8e9c6c91 100644
--- a/arch/arm64/include/asm/kvm_nested.h
+++ b/arch/arm64/include/asm/kvm_nested.h
@@ -2,13 +2,14 @@
#ifndef __ARM64_KVM_NESTED_H
#define __ARM64_KVM_NESTED_H

+#include <asm/kvm_emulate.h>
#include <linux/kvm_host.h>

static inline bool vcpu_has_nv(const struct kvm_vcpu *vcpu)
{
return (!__is_defined(__KVM_NVHE_HYPERVISOR__) &&
cpus_have_final_cap(ARM64_HAS_NESTED_VIRT) &&
- test_bit(KVM_ARM_VCPU_HAS_EL2, vcpu->arch.features));
+ vcpu_has_feature(vcpu, KVM_ARM_VCPU_HAS_EL2));
}

extern bool __check_nv_sr_forward(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 32360a5f3779..30b7e8e7b668 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -367,7 +367,6 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)

/* Force users to call KVM_ARM_VCPU_INIT */
vcpu_clear_flag(vcpu, VCPU_INITIALIZED);
- bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);

vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;

@@ -1263,7 +1262,8 @@ static bool kvm_vcpu_init_changed(struct kvm_vcpu *vcpu,
{
unsigned long features = init->features[0];

- return !bitmap_equal(vcpu->arch.features, &features, KVM_VCPU_MAX_FEATURES);
+ return !bitmap_equal(vcpu->kvm->arch.vcpu_features, &features,
+ KVM_VCPU_MAX_FEATURES);
}

static int __kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
@@ -1276,15 +1276,14 @@ static int __kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
mutex_lock(&kvm->arch.config_lock);

if (test_bit(KVM_ARCH_FLAG_VCPU_FEATURES_CONFIGURED, &kvm->arch.flags) &&
- !bitmap_equal(kvm->arch.vcpu_features, &features, KVM_VCPU_MAX_FEATURES))
+ kvm_vcpu_init_changed(vcpu, init))
goto out_unlock;

- bitmap_copy(vcpu->arch.features, &features, KVM_VCPU_MAX_FEATURES);
+ bitmap_copy(kvm->arch.vcpu_features, &features, KVM_VCPU_MAX_FEATURES);

/* Now we know what it is, we can reset it. */
kvm_reset_vcpu(vcpu);

- bitmap_copy(kvm->arch.vcpu_features, &features, KVM_VCPU_MAX_FEATURES);
set_bit(KVM_ARCH_FLAG_VCPU_FEATURES_CONFIGURED, &kvm->arch.flags);
vcpu_set_flag(vcpu, VCPU_INITIALIZED);
ret = 0;
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index 7fb4df0456de..1b79219c590c 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -554,7 +554,7 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
{
bool wants_02;

- wants_02 = test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features);
+ wants_02 = vcpu_has_feature(vcpu, KVM_ARM_VCPU_PSCI_0_2);

switch (val) {
case KVM_ARM_PSCI_0_1:
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 96ef9b7e74d4..5bb4de162cab 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -208,14 +208,14 @@ void kvm_reset_vcpu(struct kvm_vcpu *vcpu)
kvm_arch_vcpu_put(vcpu);

if (!kvm_arm_vcpu_sve_finalized(vcpu)) {
- if (test_bit(KVM_ARM_VCPU_SVE, vcpu->arch.features))
+ if (vcpu_has_feature(vcpu, KVM_ARM_VCPU_SVE))
kvm_vcpu_enable_sve(vcpu);
} else {
kvm_vcpu_reset_sve(vcpu);
}

- if (test_bit(KVM_ARM_VCPU_PTRAUTH_ADDRESS, vcpu->arch.features) ||
- test_bit(KVM_ARM_VCPU_PTRAUTH_GENERIC, vcpu->arch.features))
+ if (vcpu_has_feature(vcpu, KVM_ARM_VCPU_PTRAUTH_ADDRESS) ||
+ vcpu_has_feature(vcpu, KVM_ARM_VCPU_PTRAUTH_GENERIC))
kvm_vcpu_enable_ptrauth(vcpu);

if (vcpu_el1_is_32bit(vcpu))
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 31029f4f7be8..3546ebc469ad 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -77,7 +77,7 @@ void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu);
void kvm_vcpu_pmu_resync_el0(void);

#define kvm_vcpu_has_pmu(vcpu) \
- (test_bit(KVM_ARM_VCPU_PMU_V3, (vcpu)->arch.features))
+ (vcpu_has_feature(vcpu, KVM_ARM_VCPU_PMU_V3))

/*
* Updates the vcpu's view of the pmu events for this cpu.
diff --git a/include/kvm/arm_psci.h b/include/kvm/arm_psci.h
index 6e55b9283789..e8fb624013d1 100644
--- a/include/kvm/arm_psci.h
+++ b/include/kvm/arm_psci.h
@@ -26,7 +26,7 @@ static inline int kvm_psci_version(struct kvm_vcpu *vcpu)
* revisions. It is thus safe to return the latest, unless
* userspace has instructed us otherwise.
*/
- if (test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features)) {
+ if (vcpu_has_feature(vcpu, KVM_ARM_VCPU_PSCI_0_2)) {
if (vcpu->kvm->arch.psci_version)
return vcpu->kvm->arch.psci_version;

--
2.42.0.515.g380fc7ccd1-goog