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authorPeng Hao <peng.hao2@zte.com.cn>2018-10-14 07:09:55 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2018-10-17 00:30:11 +0200
commit0804c849f1df0992d39a37c4fc259f7f8b16f385 (patch)
tree40ab26eea50c1c904522352d56870beb6126b20b /virt
parent9943450b7b8831c5045362eed45f6fefd1986d72 (diff)
downloadlinux-aarch64-0804c849f1df0992d39a37c4fc259f7f8b16f385.tar.gz
kvm/x86 : add coalesced pio support
Coalesced pio is based on coalesced mmio and can be used for some port like rtc port, pci-host config port and so on. Specially in case of rtc as coalesced pio, some versions of windows guest access rtc frequently because of rtc as system tick. guest access rtc like this: write register index to 0x70, then write or read data from 0x71. writing 0x70 port is just as index and do nothing else. So we can use coalesced pio to handle this scene to reduce VM-EXIT time. When starting and closing a virtual machine, it will access pci-host config port frequently. So setting these port as coalesced pio can reduce startup and shutdown time. without my patch, get the vm-exit time of accessing rtc 0x70 and piix 0xcf8 using perf tools: (guest OS : windows 7 64bit) IO Port Access Samples Samples% Time% Min Time Max Time Avg time 0x70:POUT 86 30.99% 74.59% 9us 29us 10.75us (+- 3.41%) 0xcf8:POUT 1119 2.60% 2.12% 2.79us 56.83us 3.41us (+- 2.23%) with my patch IO Port Access Samples Samples% Time% Min Time Max Time Avg time 0x70:POUT 106 32.02% 29.47% 0us 10us 1.57us (+- 7.38%) 0xcf8:POUT 1065 1.67% 0.28% 0.41us 65.44us 0.66us (+- 10.55%) Signed-off-by: Peng Hao <peng.hao2@zte.com.cn> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/coalesced_mmio.c12
-rw-r--r--virt/kvm/kvm_main.c2
2 files changed, 11 insertions, 3 deletions
diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
index 9e65feb6fa58..3710342cf6ad 100644
--- a/virt/kvm/coalesced_mmio.c
+++ b/virt/kvm/coalesced_mmio.c
@@ -83,6 +83,7 @@ static int coalesced_mmio_write(struct kvm_vcpu *vcpu,
ring->coalesced_mmio[ring->last].phys_addr = addr;
ring->coalesced_mmio[ring->last].len = len;
memcpy(ring->coalesced_mmio[ring->last].data, val, len);
+ ring->coalesced_mmio[ring->last].pio = dev->zone.pio;
smp_wmb();
ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX;
spin_unlock(&dev->kvm->ring_lock);
@@ -140,6 +141,9 @@ int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
int ret;
struct kvm_coalesced_mmio_dev *dev;
+ if (zone->pio != 1 && zone->pio != 0)
+ return -EINVAL;
+
dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL);
if (!dev)
return -ENOMEM;
@@ -149,8 +153,9 @@ int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
dev->zone = *zone;
mutex_lock(&kvm->slots_lock);
- ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, zone->addr,
- zone->size, &dev->dev);
+ ret = kvm_io_bus_register_dev(kvm,
+ zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS,
+ zone->addr, zone->size, &dev->dev);
if (ret < 0)
goto out_free_dev;
list_add_tail(&dev->list, &kvm->coalesced_zones);
@@ -174,7 +179,8 @@ int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
list_for_each_entry_safe(dev, tmp, &kvm->coalesced_zones, list)
if (coalesced_mmio_in_range(dev, zone->addr, zone->size)) {
- kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS, &dev->dev);
+ kvm_io_bus_unregister_dev(kvm,
+ zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS, &dev->dev);
kvm_iodevice_destructor(&dev->dev);
}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index acc951cc2663..067b71abae00 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2949,6 +2949,8 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
#ifdef CONFIG_KVM_MMIO
case KVM_CAP_COALESCED_MMIO:
return KVM_COALESCED_MMIO_PAGE_OFFSET;
+ case KVM_CAP_COALESCED_PIO:
+ return 1;
#endif
#ifdef CONFIG_HAVE_KVM_IRQ_ROUTING
case KVM_CAP_IRQ_ROUTING: