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multi-process: PCI BAR read/write handling for proxy & remote endpoints
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Proxy device object implements handler for PCI BAR writes and reads.
The handler uses BAR_WRITE/BAR_READ message to communicate to the
remote process with the BAR address and value to be written/read.
The remote process implements handler for BAR_WRITE/BAR_READ
message.

Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: a8b76714a9688be5552c4c92d089bc9e8a4707ff.1611938319.git.jag.raman@oracle.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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@jraman567 @stefanhaRH
jraman567 authored and stefanhaRH committed Feb 4, 2021
1 parent 347f709 commit f2afdd1
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Showing 5 changed files with 168 additions and 0 deletions.
83 changes: 83 additions & 0 deletions hw/remote/message.c
View file
Expand Up @@ -16,11 +16,14 @@
#include "qapi/error.h"
#include "sysemu/runstate.h"
#include "hw/pci/pci.h"
#include "exec/memattrs.h"

static void process_config_write(QIOChannel *ioc, PCIDevice *dev,
MPQemuMsg *msg, Error **errp);
static void process_config_read(QIOChannel *ioc, PCIDevice *dev,
MPQemuMsg *msg, Error **errp);
static void process_bar_write(QIOChannel *ioc, MPQemuMsg *msg, Error **errp);
static void process_bar_read(QIOChannel *ioc, MPQemuMsg *msg, Error **errp);

void coroutine_fn mpqemu_remote_msg_loop_co(void *data)
{
Expand Down Expand Up @@ -52,6 +55,12 @@ void coroutine_fn mpqemu_remote_msg_loop_co(void *data)
case MPQEMU_CMD_PCI_CFGREAD:
process_config_read(com->ioc, pci_dev, &msg, &local_err);
break;
case MPQEMU_CMD_BAR_WRITE:
process_bar_write(com->ioc, &msg, &local_err);
break;
case MPQEMU_CMD_BAR_READ:
process_bar_read(com->ioc, &msg, &local_err);
break;
default:
error_setg(&local_err,
"Unknown command (%d) received for device %s"
Expand Down Expand Up @@ -115,3 +124,77 @@ static void process_config_read(QIOChannel *ioc, PCIDevice *dev,
getpid());
}
}

static void process_bar_write(QIOChannel *ioc, MPQemuMsg *msg, Error **errp)
{
ERRP_GUARD();
BarAccessMsg *bar_access = &msg->data.bar_access;
AddressSpace *as =
bar_access->memory ? &address_space_memory : &address_space_io;
MPQemuMsg ret = { 0 };
MemTxResult res;
uint64_t val;

if (!is_power_of_2(bar_access->size) ||
(bar_access->size > sizeof(uint64_t))) {
ret.data.u64 = UINT64_MAX;
goto fail;
}

val = cpu_to_le64(bar_access->val);

res = address_space_rw(as, bar_access->addr, MEMTXATTRS_UNSPECIFIED,
(void *)&val, bar_access->size, true);

if (res != MEMTX_OK) {
error_setg(errp, "Bad address %"PRIx64" for mem write, pid "FMT_pid".",
bar_access->addr, getpid());
ret.data.u64 = -1;
}

fail:
ret.cmd = MPQEMU_CMD_RET;
ret.size = sizeof(ret.data.u64);

if (!mpqemu_msg_send(&ret, ioc, NULL)) {
error_prepend(errp, "Error returning code to proxy, pid "FMT_pid": ",
getpid());
}
}

static void process_bar_read(QIOChannel *ioc, MPQemuMsg *msg, Error **errp)
{
ERRP_GUARD();
BarAccessMsg *bar_access = &msg->data.bar_access;
MPQemuMsg ret = { 0 };
AddressSpace *as;
MemTxResult res;
uint64_t val = 0;

as = bar_access->memory ? &address_space_memory : &address_space_io;

if (!is_power_of_2(bar_access->size) ||
(bar_access->size > sizeof(uint64_t))) {
val = UINT64_MAX;
goto fail;
}

res = address_space_rw(as, bar_access->addr, MEMTXATTRS_UNSPECIFIED,
(void *)&val, bar_access->size, false);

if (res != MEMTX_OK) {
error_setg(errp, "Bad address %"PRIx64" for mem read, pid "FMT_pid".",
bar_access->addr, getpid());
val = UINT64_MAX;
}

fail:
ret.cmd = MPQEMU_CMD_RET;
ret.data.u64 = le64_to_cpu(val);
ret.size = sizeof(ret.data.u64);

if (!mpqemu_msg_send(&ret, ioc, NULL)) {
error_prepend(errp, "Error returning code to proxy, pid "FMT_pid": ",
getpid());
}
}
6 changes: 6 additions & 0 deletions hw/remote/mpqemu-link.c
View file
Expand Up @@ -248,6 +248,12 @@ bool mpqemu_msg_valid(MPQemuMsg *msg)
return false;
}
break;
case MPQEMU_CMD_BAR_WRITE:
case MPQEMU_CMD_BAR_READ:
if ((msg->size != sizeof(BarAccessMsg)) || (msg->num_fds != 0)) {
return false;
}
break;
default:
break;
}
Expand Down
60 changes: 60 additions & 0 deletions hw/remote/proxy.c
View file
Expand Up @@ -152,3 +152,63 @@ static void pci_proxy_dev_register_types(void)
}

type_init(pci_proxy_dev_register_types)

static void send_bar_access_msg(PCIProxyDev *pdev, MemoryRegion *mr,
bool write, hwaddr addr, uint64_t *val,
unsigned size, bool memory)
{
MPQemuMsg msg = { 0 };
long ret = -EINVAL;
Error *local_err = NULL;

msg.size = sizeof(BarAccessMsg);
msg.data.bar_access.addr = mr->addr + addr;
msg.data.bar_access.size = size;
msg.data.bar_access.memory = memory;

if (write) {
msg.cmd = MPQEMU_CMD_BAR_WRITE;
msg.data.bar_access.val = *val;
} else {
msg.cmd = MPQEMU_CMD_BAR_READ;
}

ret = mpqemu_msg_send_and_await_reply(&msg, pdev, &local_err);
if (local_err) {
error_report_err(local_err);
}

if (!write) {
*val = ret;
}
}

static void proxy_bar_write(void *opaque, hwaddr addr, uint64_t val,
unsigned size)
{
ProxyMemoryRegion *pmr = opaque;

send_bar_access_msg(pmr->dev, &pmr->mr, true, addr, &val, size,
pmr->memory);
}

static uint64_t proxy_bar_read(void *opaque, hwaddr addr, unsigned size)
{
ProxyMemoryRegion *pmr = opaque;
uint64_t val;

send_bar_access_msg(pmr->dev, &pmr->mr, false, addr, &val, size,
pmr->memory);

return val;
}

const MemoryRegionOps proxy_mr_ops = {
.read = proxy_bar_read,
.write = proxy_bar_write,
.endianness = DEVICE_NATIVE_ENDIAN,
.impl = {
.min_access_size = 1,
.max_access_size = 8,
},
};
10 changes: 10 additions & 0 deletions include/hw/remote/mpqemu-link.h
View file
Expand Up @@ -37,6 +37,8 @@ typedef enum {
MPQEMU_CMD_RET,
MPQEMU_CMD_PCI_CFGWRITE,
MPQEMU_CMD_PCI_CFGREAD,
MPQEMU_CMD_BAR_WRITE,
MPQEMU_CMD_BAR_READ,
MPQEMU_CMD_MAX,
} MPQemuCmd;

Expand All @@ -52,6 +54,13 @@ typedef struct {
int len;
} PciConfDataMsg;

typedef struct {
hwaddr addr;
uint64_t val;
unsigned size;
bool memory;
} BarAccessMsg;

/**
* MPQemuMsg:
* @cmd: The remote command
Expand All @@ -71,6 +80,7 @@ typedef struct {
uint64_t u64;
PciConfDataMsg pci_conf_data;
SyncSysmemMsg sync_sysmem;
BarAccessMsg bar_access;
} data;

int fds[REMOTE_MAX_FDS];
Expand Down
9 changes: 9 additions & 0 deletions include/hw/remote/proxy.h
View file
Expand Up @@ -15,6 +15,14 @@
#define TYPE_PCI_PROXY_DEV "x-pci-proxy-dev"
OBJECT_DECLARE_SIMPLE_TYPE(PCIProxyDev, PCI_PROXY_DEV)

typedef struct ProxyMemoryRegion {
PCIProxyDev *dev;
MemoryRegion mr;
bool memory;
bool present;
uint8_t type;
} ProxyMemoryRegion;

struct PCIProxyDev {
PCIDevice parent_dev;
char *fd;
Expand All @@ -28,6 +36,7 @@ struct PCIProxyDev {
QemuMutex io_mutex;
QIOChannel *ioc;
Error *migration_blocker;
ProxyMemoryRegion region[PCI_NUM_REGIONS];
};

#endif /* PROXY_H */

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