[RFC PATCH 13/15] RISC-V: KVM: Add guest file irqbypass support

Andrew Jones
2024-11-14T16:19:21Z

Implement kvm_arch_update_irqfd_routing() which makes
irq_set_vcpu_affinity() calls whenever the assigned device updates
its target addresses and whenever the hypervisor has migrated a
VCPU to another CPU (which requires changing the guest interrupt
file).

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
---
arch/riscv/kvm/aia_imsic.c | 132 ++++++++++++++++++++++++++++++++++++-
arch/riscv/kvm/vm.c | 2 +-
2 files changed, 130 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/kvm/aia_imsic.c b/arch/riscv/kvm/aia_imsic.c
index 64b1f3713dd5..6a7c23e25f79 100644
--- a/arch/riscv/kvm/aia_imsic.c
+++ b/arch/riscv/kvm/aia_imsic.c
@@ -11,11 +11,13 @@
#include <linux/bitmap.h>
#include <linux/irqchip/riscv-imsic.h>
#include <linux/kvm_host.h>
+#include <linux/kvm_irqfd.h>
#include <linux/math.h>
#include <linux/spinlock.h>
#include <linux/swab.h>
#include <kvm/iodev.h>
#include <asm/csr.h>
+#include <asm/irq.h>

#define IMSIC_MAX_EIX (IMSIC_MAX_ID / BITS_PER_TYPE(u64))

@@ -676,6 +678,14 @@ static void imsic_swfile_update(struct kvm_vcpu *vcpu,
imsic_swfile_extirq_update(vcpu);
}

+static u64 kvm_riscv_aia_msi_addr_mask(struct kvm_aia *aia)
+{
+ u64 group_mask = BIT(aia->nr_group_bits) - 1;
+
+ return (group_mask << (aia->nr_group_shift - IMSIC_MMIO_PAGE_SHIFT)) |
+ (BIT(aia->nr_hart_bits + aia->nr_guest_bits) - 1);
+}
+
void kvm_riscv_vcpu_aia_imsic_release(struct kvm_vcpu *vcpu)
{
unsigned long flags;
@@ -730,7 +740,120 @@ void kvm_riscv_vcpu_aia_imsic_release(struct kvm_vcpu *vcpu)
int kvm_arch_update_irqfd_routing(struct kvm *kvm, unsigned int host_irq,
uint32_t guest_irq, bool set)
{
- return -ENXIO;
+ struct irq_data *irqdata = irq_get_irq_data(host_irq);
+ struct kvm_irq_routing_table *irq_rt;
+ struct kvm_vcpu *vcpu;
+ unsigned long tmp, flags;
+ int idx, ret = -ENXIO;
+
+ if (!set)
+ return irq_set_vcpu_affinity(host_irq, NULL);
+
+ idx = srcu_read_lock(&kvm->irq_srcu);
+ irq_rt = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu);
+ if (guest_irq >= irq_rt->nr_rt_entries ||
+ hlist_empty(&irq_rt->map[guest_irq])) {
+ pr_warn_once("no route for guest_irq %u/%u (broken user space?)\n",
+ guest_irq, irq_rt->nr_rt_entries);
+ goto out;
+ }
+
+ kvm_for_each_vcpu(tmp, vcpu, kvm) {
+ struct imsic *imsic = vcpu->arch.aia_context.imsic_state;
+ gpa_t ippn = vcpu->arch.aia_context.imsic_addr >> IMSIC_MMIO_PAGE_SHIFT;
+ struct kvm_aia *aia = &kvm->arch.aia;
+ struct kvm_kernel_irq_routing_entry *e;
+
+ hlist_for_each_entry(e, &irq_rt->map[guest_irq], link) {
+ struct msi_msg msg[2] = {
+ {
+ .address_hi = e->msi.address_hi,
+ .address_lo = e->msi.address_lo,
+ .data = e->msi.data,
+ },
+ };
+ struct riscv_iommu_vcpu_info vcpu_info = {
+ .msi_addr_mask = kvm_riscv_aia_msi_addr_mask(aia),
+ .group_index_bits = aia->nr_group_bits,
+ .group_index_shift = aia->nr_group_shift,
+ };
+ gpa_t target, tppn;
+
+ if (e->type != KVM_IRQ_ROUTING_MSI)
+ continue;
+
+ target = ((gpa_t)e->msi.address_hi << 32) | e->msi.address_lo;
+ tppn = target >> IMSIC_MMIO_PAGE_SHIFT;
+
+ WARN_ON(target & (IMSIC_MMIO_PAGE_SZ - 1));
+
+ if (ippn != tppn)
+ continue;
+
+ vcpu_info.msi_addr_pattern = tppn & ~vcpu_info.msi_addr_mask;
+ vcpu_info.gpa = target;
+
+ read_lock_irqsave(&imsic->vsfile_lock, flags);
+
+ if (WARN_ON_ONCE(imsic->vsfile_cpu < 0)) {
+ read_unlock_irqrestore(&imsic->vsfile_lock, flags);
+ goto out;
+ }
+
+ vcpu_info.hpa = imsic->vsfile_pa;
+
+ ret = irq_set_vcpu_affinity(host_irq, &vcpu_info);
+ if (ret) {
+ read_unlock_irqrestore(&imsic->vsfile_lock, flags);
+ goto out;
+ }
+
+ irq_data_get_irq_chip(irqdata)->irq_write_msi_msg(irqdata, msg);
+
+ read_unlock_irqrestore(&imsic->vsfile_lock, flags);
+ }
+ }
+
+ ret = 0;
+out:
+ srcu_read_unlock(&kvm->irq_srcu, idx);
+ return ret;
+}
+
+static int kvm_riscv_vcpu_irq_update(struct kvm_vcpu *vcpu)
+{
+ struct kvm *kvm = vcpu->kvm;
+ struct imsic *imsic = vcpu->arch.aia_context.imsic_state;
+ struct kvm_aia *aia = &kvm->arch.aia;
+ u64 mask = kvm_riscv_aia_msi_addr_mask(aia);
+ u64 target = vcpu->arch.aia_context.imsic_addr;
+ struct riscv_iommu_vcpu_info vcpu_info = {
+ .msi_addr_pattern = (target >> IMSIC_MMIO_PAGE_SHIFT) & ~mask,
+ .msi_addr_mask = mask,
+ .group_index_bits = aia->nr_group_bits,
+ .group_index_shift = aia->nr_group_shift,
+ .gpa = target,
+ .hpa = imsic->vsfile_pa,
+ };
+ struct kvm_kernel_irqfd *irqfd;
+ int host_irq, ret;
+
+ spin_lock_irq(&kvm->irqfds.lock);
+
+ list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
+ if (!irqfd->producer)
+ continue;
+ host_irq = irqfd->producer->irq;
+ ret = irq_set_vcpu_affinity(host_irq, &vcpu_info);
+ if (ret) {
+ spin_unlock_irq(&kvm->irqfds.lock);
+ return ret;
+ }
+ }
+
+ spin_unlock_irq(&kvm->irqfds.lock);
+
+ return 0;
}

int kvm_riscv_vcpu_aia_imsic_update(struct kvm_vcpu *vcpu)
@@ -797,14 +920,17 @@ int kvm_riscv_vcpu_aia_imsic_update(struct kvm_vcpu *vcpu)
if (ret)
goto fail_free_vsfile_hgei;

- /* TODO: Update the IOMMU mapping ??? */
-
/* Update new IMSIC VS-file details in IMSIC context */
write_lock_irqsave(&imsic->vsfile_lock, flags);
+
imsic->vsfile_hgei = new_vsfile_hgei;
imsic->vsfile_cpu = vcpu->cpu;
imsic->vsfile_va = new_vsfile_va;
imsic->vsfile_pa = new_vsfile_pa;
+
+ /* Update the IOMMU mapping */
+ kvm_riscv_vcpu_irq_update(vcpu);
+
write_unlock_irqrestore(&imsic->vsfile_lock, flags);

/*
diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
index 9c5837518c1a..5f697d9a37da 100644
--- a/arch/riscv/kvm/vm.c
+++ b/arch/riscv/kvm/vm.c
@@ -78,7 +78,7 @@ EXPORT_SYMBOL_GPL(kvm_arch_has_assigned_device);

bool kvm_arch_has_irq_bypass(void)
{
- return false;
+ return true;
}

int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons,
--
2.47.0