KVM: arm64: Track presence of SPE/TRBE in kvm_host_data instead of vCPU

Add flags to kvm_host_data to track if SPE/TRBE is present +
programmable on a per-CPU basis. Set the flags up at init rather than
vcpu_load() as the programmability of these buffers is unlikely to
change.

Reviewed-by: James Clark <james.clark@linaro.org>
Tested-by: James Clark <james.clark@linaro.org>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20241219224116.3941496-4-oliver.upton@linux.dev
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 064f5dfca7f42d4ef5860928c8edf7eb711dcb77..fb252d5408500159f2718ad2379c8b7d7c83ca92 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -610,6 +610,10 @@ struct cpu_sve_state {
  * field.
  */
 struct kvm_host_data {
+#define KVM_HOST_DATA_FLAG_HAS_SPE     0
+#define KVM_HOST_DATA_FLAG_HAS_TRBE    1
+       unsigned long flags;
+
        struct kvm_cpu_context host_ctxt;
 
        /*
@@ -911,10 +915,6 @@ struct kvm_vcpu_arch {
 #define EXCEPT_AA64_EL2_SERR   __vcpu_except_flags(7)
 /* Guest debug is live */
 #define DEBUG_DIRTY            __vcpu_single_flag(iflags, BIT(4))
-/* Save SPE context if active  */
-#define DEBUG_STATE_SAVE_SPE   __vcpu_single_flag(iflags, BIT(5))
-/* Save TRBE context if active  */
-#define DEBUG_STATE_SAVE_TRBE  __vcpu_single_flag(iflags, BIT(6))
 
 /* SVE enabled for host EL0 */
 #define HOST_SVE_ENABLED       __vcpu_single_flag(sflags, BIT(0))
@@ -1310,6 +1310,13 @@ DECLARE_KVM_HYP_PER_CPU(struct kvm_host_data, kvm_host_data);
         &this_cpu_ptr_hyp_sym(kvm_host_data)->f)
 #endif
 
+#define host_data_test_flag(flag)                                      \
+       (test_bit(KVM_HOST_DATA_FLAG_##flag, host_data_ptr(flags)))
+#define host_data_set_flag(flag)                                       \
+       set_bit(KVM_HOST_DATA_FLAG_##flag, host_data_ptr(flags))
+#define host_data_clear_flag(flag)                                     \
+       clear_bit(KVM_HOST_DATA_FLAG_##flag, host_data_ptr(flags))
+
 /* Check whether the FP regs are owned by the guest */
 static inline bool guest_owns_fp_regs(void)
 {
@@ -1370,10 +1377,6 @@ static inline bool kvm_pmu_counter_deferred(struct perf_event_attr *attr)
        return (!has_vhe() && attr->exclude_host);
 }
 
-/* Flags for host debug state */
-void kvm_arch_vcpu_load_debug_state_flags(struct kvm_vcpu *vcpu);
-void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu);
-
 #ifdef CONFIG_KVM
 void kvm_set_pmu_events(u64 set, struct perf_event_attr *attr);
 void kvm_clr_pmu_events(u64 clr);

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index ab1bf9ccf385e97816e29a7273b91d440c076abd..3822774840e1fbcca886729cdf6706b54337da38 100644 (file)
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -617,15 +617,12 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 
        vcpu_set_pauth_traps(vcpu);
 
-       kvm_arch_vcpu_load_debug_state_flags(vcpu);
-
        if (!cpumask_test_cpu(cpu, vcpu->kvm->arch.supported_cpus))
                vcpu_set_on_unsupported_cpu(vcpu);
 }
 
 void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 {
-       kvm_arch_vcpu_put_debug_state_flags(vcpu);
        kvm_arch_vcpu_put_fp(vcpu);
        if (has_vhe())
                kvm_vcpu_put_vhe(vcpu);

diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c
index d8ea6fe6a2a226a4f5840a26d8ae4808dae83934..1ee2fd765b62ef90993533bd6f032c0a28ff17f4 100644 (file)
--- a/arch/arm64/kvm/debug.c
+++ b/arch/arm64/kvm/debug.c
@@ -294,40 +294,22 @@ void kvm_arm_clear_debug(struct kvm_vcpu *vcpu)
        }
 }
 
-void kvm_arch_vcpu_load_debug_state_flags(struct kvm_vcpu *vcpu)
+void kvm_init_host_debug_data(void)
 {
-       u64 dfr0;
+       u64 dfr0 = read_sysreg(id_aa64dfr0_el1);
+
+       if (cpuid_feature_extract_signed_field(dfr0, ID_AA64DFR0_EL1_PMUVer_SHIFT) > 0)
+               *host_data_ptr(nr_event_counters) = FIELD_GET(ARMV8_PMU_PMCR_N,
+                                                             read_sysreg(pmcr_el0));
 
-       /* For VHE, there is nothing to do */
        if (has_vhe())
                return;
 
-       dfr0 = read_sysreg(id_aa64dfr0_el1);
-       /*
-        * If SPE is present on this CPU and is available at current EL,
-        * we may need to check if the host state needs to be saved.
-        */
        if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_PMSVer_SHIFT) &&
-           !(read_sysreg_s(SYS_PMBIDR_EL1) & BIT(PMBIDR_EL1_P_SHIFT)))
-               vcpu_set_flag(vcpu, DEBUG_STATE_SAVE_SPE);
+           !(read_sysreg_s(SYS_PMBIDR_EL1) & PMBIDR_EL1_P))
+               host_data_set_flag(HAS_SPE);
 
-       /* Check if we have TRBE implemented and available at the host */
        if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_TraceBuffer_SHIFT) &&
            !(read_sysreg_s(SYS_TRBIDR_EL1) & TRBIDR_EL1_P))
-               vcpu_set_flag(vcpu, DEBUG_STATE_SAVE_TRBE);
-}
-
-void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu)
-{
-       vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE_SPE);
-       vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE_TRBE);
-}
-
-void kvm_init_host_debug_data(void)
-{
-       u64 dfr0 = read_sysreg(id_aa64dfr0_el1);
-
-       if (cpuid_feature_extract_signed_field(dfr0, ID_AA64DFR0_EL1_PMUVer_SHIFT) > 0)
-               *host_data_ptr(nr_event_counters) = FIELD_GET(ARMV8_PMU_PMCR_N,
-                                                             read_sysreg(pmcr_el0));
+               host_data_set_flag(HAS_TRBE);
 }

diff --git a/arch/arm64/kvm/hyp/nvhe/debug-sr.c b/arch/arm64/kvm/hyp/nvhe/debug-sr.c
index 1e2a26d0196e52bb9b5c11aa95fe5d4fd171f0e0..858bb38e273f8bbd141187cd0d4df130d7dfb374 100644 (file)
--- a/arch/arm64/kvm/hyp/nvhe/debug-sr.c
+++ b/arch/arm64/kvm/hyp/nvhe/debug-sr.c
@@ -82,10 +82,10 @@ static void __debug_restore_trace(u64 trfcr_el1)
 void __debug_save_host_buffers_nvhe(struct kvm_vcpu *vcpu)
 {
        /* Disable and flush SPE data generation */
-       if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_SPE))
+       if (host_data_test_flag(HAS_SPE))
                __debug_save_spe(host_data_ptr(host_debug_state.pmscr_el1));
        /* Disable and flush Self-Hosted Trace generation */
-       if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_TRBE))
+       if (host_data_test_flag(HAS_TRBE))
                __debug_save_trace(host_data_ptr(host_debug_state.trfcr_el1));
 }
 
@@ -96,9 +96,9 @@ void __debug_switch_to_guest(struct kvm_vcpu *vcpu)
 
 void __debug_restore_host_buffers_nvhe(struct kvm_vcpu *vcpu)
 {
-       if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_SPE))
+       if (host_data_test_flag(HAS_SPE))
                __debug_restore_spe(*host_data_ptr(host_debug_state.pmscr_el1));
-       if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_TRBE))
+       if (host_data_test_flag(HAS_TRBE))
                __debug_restore_trace(*host_data_ptr(host_debug_state.trfcr_el1));
 }