[PATCH v2 33/43] arm64: rme: Enable PMU support with a realm guest

Steven Price
2024-04-12T08:44:36Z

Use the PMU registers from the RmiRecExit structure to identify when an
overflow interrupt is due and inject it into the guest. Also hook up the
configuration option for enabling the PMU within the guest.

When entering a realm guest with a PMU interrupt pending, it is
necessary to disable the physical interrupt. Otherwise when the RMM
restores the PMU state the physical interrupt will trigger causing an
immediate exit back to the host. The guest is expected to acknowledge
the interrupt causing a host exit (to update the GIC state) which gives
the opportunity to re-enable the physical interrupt before the next PMU
event.

Number of PMU counters is configured by the VMM by writing to PMCR.N.

Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
arch/arm64/kvm/arm.c | 15 +++++++++++++++
arch/arm64/kvm/guest.c | 7 +++++++
arch/arm64/kvm/pmu-emul.c | 4 +++-
arch/arm64/kvm/rme.c | 8 ++++++++
arch/arm64/kvm/sys_regs.c | 2 +-
5 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index dcd9089877f3..2aad83053b62 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -15,6 +15,7 @@
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/mman.h>
+#include <linux/perf/arm_pmu.h>
#include <linux/sched.h>
#include <linux/kvm.h>
#include <linux/kvm_irqfd.h>
@@ -1075,6 +1076,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
run->exit_reason = KVM_EXIT_UNKNOWN;
run->flags = 0;
while (ret > 0) {
+ bool pmu_stopped = false;
+
/*
* Check conditions before entering the guest
*/
@@ -1106,6 +1109,15 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)

kvm_pmu_flush_hwstate(vcpu);

+ if (vcpu_is_rec(vcpu)) {
+ struct kvm_pmu *pmu = &vcpu->arch.pmu;
+
+ if (pmu->irq_level) {
+ pmu_stopped = true;
+ arm_pmu_set_phys_irq(false);
+ }
+ }
+
local_irq_disable();

kvm_vgic_flush_hwstate(vcpu);
@@ -1208,6 +1220,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)

preempt_enable();

+ if (pmu_stopped)
+ arm_pmu_set_phys_irq(true);
+
/*
* The ARMv8 architecture doesn't give the hypervisor
* a mechanism to prevent a guest from dropping to AArch32 EL0
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 5223a828a344..d35367cf527d 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -782,6 +782,8 @@ int kvm_arm_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
return kvm_arm_sys_reg_get_reg(vcpu, reg);
}

+#define KVM_REG_ARM_PMCR_EL0 ARM64_SYS_REG(3, 3, 9, 12, 0)
+
/*
* The RMI ABI only enables setting the lower GPRs (x0-x7) and PC.
* All other registers are reset to architectural or otherwise defined reset
@@ -800,6 +802,11 @@ static bool validate_realm_set_reg(struct kvm_vcpu *vcpu,
case KVM_REG_ARM_CORE_REG(regs.pc):
return true;
}
+ } else {
+ switch (reg->id) {
+ case KVM_REG_ARM_PMCR_EL0:
+ return true;
+ }
}

return false;
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index a35ce10e0a9f..ce7c8e55d904 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -341,7 +341,9 @@ static u64 kvm_pmu_overflow_status(struct kvm_vcpu *vcpu)
{
u64 reg = 0;

- if ((kvm_vcpu_read_pmcr(vcpu) & ARMV8_PMU_PMCR_E)) {
+ if (vcpu_is_rec(vcpu)) {
+ reg = vcpu->arch.rec.run->exit.pmu_ovf_status;
+ } else if ((kvm_vcpu_read_pmcr(vcpu) & ARMV8_PMU_PMCR_E)) {
reg = __vcpu_sys_reg(vcpu, PMOVSSET_EL0);
reg &= __vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
reg &= __vcpu_sys_reg(vcpu, PMINTENSET_EL1);
diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c
index ae9fd12c4e7d..e60a1196a2fe 100644
--- a/arch/arm64/kvm/rme.c
+++ b/arch/arm64/kvm/rme.c
@@ -314,6 +314,11 @@ static int realm_create_rd(struct kvm *kvm)
params->rtt_base = kvm->arch.mmu.pgd_phys;
params->vmid = realm->vmid;

+ if (kvm->arch.arm_pmu) {
+ params->pmu_num_ctrs = kvm->arch.pmcr_n;
+ params->flags |= RMI_REALM_PARAM_FLAG_PMU;
+ }
+
params_phys = virt_to_phys(params);

if (rmi_realm_create(rd_phys, params_phys)) {
@@ -1366,6 +1371,9 @@ int kvm_create_rec(struct kvm_vcpu *vcpu)
if (!vcpu_has_feature(vcpu, KVM_ARM_VCPU_PSCI_0_2))
return -EINVAL;

+ if (vcpu->kvm->arch.arm_pmu && !kvm_vcpu_has_pmu(vcpu))
+ return -EINVAL;
+
BUILD_BUG_ON(sizeof(*params) > PAGE_SIZE);
BUILD_BUG_ON(sizeof(*rec->run) > PAGE_SIZE);

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index c9f4f387155f..60452c6519a4 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1279,7 +1279,7 @@ static int set_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r,
* implements. Ignore this error to maintain compatibility
* with the existing KVM behavior.
*/
- if (!kvm_vm_has_ran_once(kvm) &&
+ if (!kvm_vm_has_ran_once(kvm) && !kvm_realm_is_created(kvm) &&
new_n <= kvm_arm_pmu_get_max_counters(kvm))
kvm->arch.pmcr_n = new_n;

--
2.34.1