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[common] ivshmem: do not create dmabuf for simple mmap

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It used to be the case that you need to create dmabuf for kvmfr devices
to be able to mmap them. But after #457, this is no longer needed.

Directly mmaping the kvmfr device has the advantage of avoiding the
creation of a dmabuf, which has cost (e.g. the list of pages, the
scatterlist, etc.).
This commit is contained in:
Quantum 2021-02-07 16:00:07 -05:00 committed by Geoffrey McRae
parent 328f9078ee
commit 62b27760ea
1 changed files with 11 additions and 31 deletions
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42
common/src/platform/linux/ivshmem.c
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@ -37,9 +37,9 @@ Place, Suite 330, Boston, MA 02111-1307 USA
struct IVSHMEMInfo struct IVSHMEMInfo
{ {
int devFd; int devFd;
int dmaFd; int size;
int size; bool hasDMA;
}; };
static bool ivshmemDeviceValidator(struct Option * opt, const char ** error) static bool ivshmemDeviceValidator(struct Option * opt, const char ** error)
@ -119,8 +119,7 @@ bool ivshmemOpenDev(struct IVSHMEM * dev, const char * shmDevice)
unsigned int devSize; unsigned int devSize;
int devFd = -1; int devFd = -1;
int dmaFd = -1; bool hasDMA;
int mapFd = -1;
dev->opaque = NULL; dev->opaque = NULL;
@ -138,22 +137,7 @@ bool ivshmemOpenDev(struct IVSHMEM * dev, const char * shmDevice)
// get the device size // get the device size
devSize = ioctl(devFd, KVMFR_DMABUF_GETSIZE, 0); devSize = ioctl(devFd, KVMFR_DMABUF_GETSIZE, 0);
const struct kvmfr_dmabuf_create create = hasDMA = true;
{
.flags = KVMFR_DMABUF_FLAG_CLOEXEC,
.offset = 0x0,
.size = devSize
};
dmaFd = ioctl(devFd, KVMFR_DMABUF_CREATE, &create);
if (dmaFd < 0)
{
DEBUG_ERROR("Failed to create the dma buffer");
close(devFd);
return false;
}
mapFd = dmaFd;
} }
else else
{ {
@ -174,10 +158,10 @@ bool ivshmemOpenDev(struct IVSHMEM * dev, const char * shmDevice)
return false; return false;
} }
mapFd = devFd; hasDMA = false;
} }
void * map = mmap(0, devSize, PROT_READ | PROT_WRITE, MAP_SHARED, mapFd, 0); void * map = mmap(0, devSize, PROT_READ | PROT_WRITE, MAP_SHARED, devFd, 0);
if (map == MAP_FAILED) if (map == MAP_FAILED)
{ {
DEBUG_ERROR("Failed to map the shared memory device: %s", shmDevice); DEBUG_ERROR("Failed to map the shared memory device: %s", shmDevice);
@ -187,9 +171,9 @@ bool ivshmemOpenDev(struct IVSHMEM * dev, const char * shmDevice)
struct IVSHMEMInfo * info = struct IVSHMEMInfo * info =
(struct IVSHMEMInfo *)malloc(sizeof(struct IVSHMEMInfo)); (struct IVSHMEMInfo *)malloc(sizeof(struct IVSHMEMInfo));
info->size = devSize; info->size = devSize;
info->devFd = devFd; info->devFd = devFd;
info->dmaFd = dmaFd; info->hasDMA = hasDMA;
dev->opaque = info; dev->opaque = info;
dev->size = devSize; dev->size = devSize;
@ -208,10 +192,6 @@ void ivshmemClose(struct IVSHMEM * dev)
(struct IVSHMEMInfo *)dev->opaque; (struct IVSHMEMInfo *)dev->opaque;
munmap(dev->mem, info->size); munmap(dev->mem, info->size);
if (info->dmaFd >= 0)
close(info->dmaFd);
close(info->devFd); close(info->devFd);
free(info); free(info);
@ -232,7 +212,7 @@ bool ivshmemHasDMA(struct IVSHMEM * dev)
struct IVSHMEMInfo * info = struct IVSHMEMInfo * info =
(struct IVSHMEMInfo *)dev->opaque; (struct IVSHMEMInfo *)dev->opaque;
return info->dmaFd >= 0; return info->hasDMA;
} }
int ivshmemGetDMABuf(struct IVSHMEM * dev, uint64_t offset, uint64_t size) int ivshmemGetDMABuf(struct IVSHMEM * dev, uint64_t offset, uint64_t size)