On Mon, Jul 27, 2020 at 04:46:21PM +0800, Hogan Wang wrote: > The i440fx and q35 machines integrate i440FX or MCH PCI device by default. > Refer to i440FX and ICH9-LPC spcifications, there are some reserved > configuration registers can used to save/restore PCIHostState.config_reg. > It's nasty but friendly to old ones. > > Reproducer steps: > step 1. Make modifications to seabios and qemu for increase reproduction > efficiency, write 0xf0 to 0x402 port notify qemu to stop vcpu after > 0x0cf8 port wrote i440 configure register. qemu stop vcpu when catch > 0x402 port wrote 0xf0. > > seabios:/src/hw/pci.c > @@ -52,6 +52,11 @@ void pci_config_writeb(u16 bdf, u32 addr, u8 val) > writeb(mmconfig_addr(bdf, addr), val); > } else { > outl(ioconfig_cmd(bdf, addr), PORT_PCI_CMD); > + if (bdf == 0 && addr == 0x72 && val == 0xa) { > + dprintf(1, "stop vcpu\n"); > + outb(0xf0, 0x402); // notify qemu to stop vcpu > + dprintf(1, "resume vcpu\n"); > + } > outb(val, PORT_PCI_DATA + (addr & 3)); > } > } > > qemu:hw/char/debugcon.c > @@ -60,6 +61,9 @@ static void debugcon_ioport_write(void *opaque, hwaddr > addr, uint64_t val, > printf(" [debugcon: write addr=0x%04" HWADDR_PRIx " val=0x%02" PRIx64 > "]\n", addr, val); > #endif > > + if (ch == 0xf0) { > + vm_stop(RUN_STATE_PAUSED); > + } > /* XXX this blocks entire thread. Rewrite to use > * qemu_chr_fe_write and background I/O callbacks */ > qemu_chr_fe_write_all(&s->chr, &ch, 1); > > step 2. start vm1 by the following command line, and then vm stopped. > $ qemu-system-x86_64 -machine pc-i440fx-5.0,accel=kvm\ > -netdev tap,ifname=tap-test,id=hostnet0,vhost=on,downscript=no,script=no\ > -device > virtio-net-pci,netdev=hostnet0,id=net0,bus=pci.0,addr=0x13,bootindex=3\ > -device cirrus-vga,id=video0,vgamem_mb=16,bus=pci.0,addr=0x2\ > -chardev file,id=seabios,path=/var/log/test.seabios,append=on\ > -device isa-debugcon,iobase=0x402,chardev=seabios\ > -monitor stdio > > step 3. start vm2 to accept vm1 state. > $ qemu-system-x86_64 -machine pc-i440fx-5.0,accel=kvm\ > -netdev tap,ifname=tap-test1,id=hostnet0,vhost=on,downscript=no,script=no\ > -device > virtio-net-pci,netdev=hostnet0,id=net0,bus=pci.0,addr=0x13,bootindex=3\ > -device cirrus-vga,id=video0,vgamem_mb=16,bus=pci.0,addr=0x2\ > -chardev file,id=seabios,path=/var/log/test.seabios,append=on\ > -device isa-debugcon,iobase=0x402,chardev=seabios\ > -monitor stdio \ > -incoming tcp:127.0.0.1:8000 > > step 4. execute the following qmp command in vm1 to migrate. > (qemu) migrate tcp:127.0.0.1:8000 > > step 5. execute the following qmp command in vm2 to resume vcpu. > (qemu) cont > > Before this patch, we can get KVM "emulation failure" error on vm2. > This patch can fix it. > > Signed-off-by: Hogan Wang <hogan.w...@huawei.com>
Question - did you test that this migrates successfully to old QEMU too? Thanks! And I guess this needs a CC stable? > --- > hw/pci-host/i440fx.c | 31 +++++++++++++++++++++++++++++++ > hw/pci-host/q35.c | 30 ++++++++++++++++++++++++++++++ > 2 files changed, 61 insertions(+) > > diff --git a/hw/pci-host/i440fx.c b/hw/pci-host/i440fx.c > index 8ed2417f0c..b78c8bc5f9 100644 > --- a/hw/pci-host/i440fx.c > +++ b/hw/pci-host/i440fx.c > @@ -64,6 +64,14 @@ typedef struct I440FXState { > */ > #define I440FX_COREBOOT_RAM_SIZE 0x57 > > +/* Older I440FX machines (5.0 and older) not support i440FX-pcihost state > + * migration, use some reserved INTEL 82441 configuration registers to > + * save/restore i440FX-pcihost config register. Refer to [INTEL 440FX PCISET > + * 82441FX PCI AND MEMORY CONTROLLER (PMC) AND 82442FX DATA BUS ACCELERATOR > + * (DBX) Table 1. PMC Configuration Space] > + */ > +#define I440FX_PCI_HOST_CONFIG_REG 0x94 > + > static void i440fx_update_memory_mappings(PCII440FXState *d) > { > int i; > @@ -98,8 +106,30 @@ static void i440fx_write_config(PCIDevice *dev, > static int i440fx_post_load(void *opaque, int version_id) > { > PCII440FXState *d = opaque; > + PCIDevice *dev; > + PCIHostState *s = OBJECT_CHECK(PCIHostState, > + object_resolve_path("/machine/i440fx", > NULL), > + TYPE_PCI_HOST_BRIDGE); > > i440fx_update_memory_mappings(d); > + > + if (!s->mig_enabled) { > + dev = PCI_DEVICE(d); > + s->config_reg = > pci_get_long(&dev->config[I440FX_PCI_HOST_CONFIG_REG]); > + } > + return 0; > +} > + > +static int i440fx_pre_save(void *opaque) > +{ > + PCIDevice *dev = opaque; > + PCIHostState *s = OBJECT_CHECK(PCIHostState, > + object_resolve_path("/machine/i440fx", > NULL), > + TYPE_PCI_HOST_BRIDGE); > + if (!s->mig_enabled) { > + pci_set_long(&dev->config[I440FX_PCI_HOST_CONFIG_REG], > + s->config_reg); > + } > return 0; > } > > @@ -107,6 +137,7 @@ static const VMStateDescription vmstate_i440fx = { > .name = "I440FX", > .version_id = 3, > .minimum_version_id = 3, > + .pre_save = i440fx_pre_save, > .post_load = i440fx_post_load, > .fields = (VMStateField[]) { > VMSTATE_PCI_DEVICE(parent_obj, PCII440FXState), > diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c > index b67cb9c29f..bed66be181 100644 > --- a/hw/pci-host/q35.c > +++ b/hw/pci-host/q35.c > @@ -43,6 +43,15 @@ > > #define Q35_PCI_HOST_HOLE64_SIZE_DEFAULT (1ULL << 35) > > +/* Older Q35 machines (5.0 and older) not support q35-pcihost state > + * migration, use some reserved INTEL MCH configuration registers to > + * save/restore q35-pcihost config register. Refer to [Intel 3 Series > + * Chipset Family Datasheet Table 5-1. DRAM Controller Register Address > + * Map (D0:F0)] > + */ > +#define Q35_PCI_HOST_CONFIG_REG 0x70 > + > + > static void q35_host_realize(DeviceState *dev, Error **errp) > { > PCIHostState *pci = PCI_HOST_BRIDGE(dev); > @@ -513,7 +522,27 @@ static void mch_update(MCHPCIState *mch) > static int mch_post_load(void *opaque, int version_id) > { > MCHPCIState *mch = opaque; > + PCIDevice *dev; > + PCIHostState *s = OBJECT_CHECK(PCIHostState, > + object_resolve_path("/machine/q35", NULL), > + TYPE_PCI_HOST_BRIDGE); > mch_update(mch); > + if (!s->mig_enabled) { > + dev = PCI_DEVICE(mch); > + s->config_reg = pci_get_long(&dev->config[Q35_PCI_HOST_CONFIG_REG]); > + } > + return 0; > +} > + > +static int mch_pre_save(void *opaque) > +{ > + PCIDevice *dev = opaque; > + PCIHostState *s = OBJECT_CHECK(PCIHostState, > + object_resolve_path("/machine/q35", NULL), > + TYPE_PCI_HOST_BRIDGE); > + if (!s->mig_enabled) { > + pci_set_long(&dev->config[Q35_PCI_HOST_CONFIG_REG], s->config_reg); > + } > return 0; > } > > @@ -521,6 +550,7 @@ static const VMStateDescription vmstate_mch = { > .name = "mch", > .version_id = 1, > .minimum_version_id = 1, > + .pre_save = mch_pre_save, > .post_load = mch_post_load, > .fields = (VMStateField[]) { > VMSTATE_PCI_DEVICE(parent_obj, MCHPCIState), > -- > 2.27.0 >