On 09/27/18 11:21, Laszlo Ersek wrote: > On 09/27/18 07:48, Gerd Hoffmann wrote: >> Hi, >> >>>> Maybe using memdev file backend with manually created sparse file >>>> might actually work (with preallocate disabled) >>> >>> Thanks, this sounds like a good idea. >>> >>> I see shm_open() is used heavily in ivshmem-related tests. I haven't >>> looked much at shm_open() before. (I've always known it existed in >>> POSIX, but I've never cared.) >> >> How about improving the lovely pci-testdev we have a bit? Then we can >> have huge pci bars without needing backing storage for them ... > > Earlier I checked > > qemu-system-x86_64 -device pci-testdev,\? > > briefly. I didn't see anything relevant and figured it was out of scope. > > ( > Actually, I've thought of yet another thing: the resource reservation > capability for PCIe Root Ports. The 64-bit reservation field in that cap > structure should be perfectly suitable for this testing. > > Except, of course, SeaBIOS only handles the bus number reservation > field, at this time. :/ > ) > > Looking at "docs/specs/pci-testdev.txt" now, extending the PCI testdev > looks like a separate project to me. We're getting quite far from the > original goal. I totally agree that if the PCI testdev already had this > ability, it would be a perfect fit, but I don't think I can personally > take that on now.
I realize you pasted a prototype patch below (thanks for that!), but it doesn't update the documentation. I wouldn't like to dig down another design rabbit hole here. If you can pursue upstreaming this change, I can definitely delay my series, and use the enhanced pci testdev as a reproducer. But, I'm not explicitly asking you to pursue it -- none of this classifies as a "serious bug", so these patches might not be the best uses of our times. Laszlo >> =========================== cut here =========================== >> From 05cfced149b0b5c953391666c3151034bc7fe88b Mon Sep 17 00:00:00 2001 >> From: Gerd Hoffmann <kra...@redhat.com> >> Date: Thu, 27 Sep 2018 07:43:10 +0200 >> Subject: [PATCH] pci-testdev: add optional memory bar >> >> Add memory bar to pci-testdev. Size is configurable using the membar >> property. Setting the size to zero (default) turns it off. >> >> Signed-off-by: Gerd Hoffmann <kra...@redhat.com> >> --- >> hw/misc/pci-testdev.c | 18 ++++++++++++++++++ >> 1 file changed, 18 insertions(+) >> >> diff --git a/hw/misc/pci-testdev.c b/hw/misc/pci-testdev.c >> index 32041f535f..af4d678ee4 100644 >> --- a/hw/misc/pci-testdev.c >> +++ b/hw/misc/pci-testdev.c >> @@ -85,6 +85,9 @@ typedef struct PCITestDevState { >> MemoryRegion portio; >> IOTest *tests; >> int current; >> + >> + size_t membar_size; >> + MemoryRegion membar; >> } PCITestDevState; >> >> #define TYPE_PCI_TEST_DEV "pci-testdev" >> @@ -253,6 +256,15 @@ static void pci_testdev_realize(PCIDevice *pci_dev, >> Error **errp) >> pci_register_bar(pci_dev, 0, PCI_BASE_ADDRESS_SPACE_MEMORY, &d->mmio); >> pci_register_bar(pci_dev, 1, PCI_BASE_ADDRESS_SPACE_IO, &d->portio); >> >> + if (d->membar_size) { >> + memory_region_init(&d->membar, OBJECT(d), "membar", d->membar_size); >> + pci_register_bar(pci_dev, 2, >> + PCI_BASE_ADDRESS_SPACE_MEMORY | >> + PCI_BASE_ADDRESS_MEM_PREFETCH | >> + PCI_BASE_ADDRESS_MEM_TYPE_64, >> + &d->membar); >> + } >> + >> d->current = -1; >> d->tests = g_malloc0(IOTEST_MAX * sizeof *d->tests); >> for (i = 0; i < IOTEST_MAX; ++i) { >> @@ -305,6 +317,11 @@ static void qdev_pci_testdev_reset(DeviceState *dev) >> pci_testdev_reset(d); >> } >> >> +static Property pci_testdev_properties[] = { >> + DEFINE_PROP_SIZE("membar", PCITestDevState, membar_size, 0), >> + DEFINE_PROP_END_OF_LIST(), >> +}; >> + >> static void pci_testdev_class_init(ObjectClass *klass, void *data) >> { >> DeviceClass *dc = DEVICE_CLASS(klass); >> @@ -319,6 +336,7 @@ static void pci_testdev_class_init(ObjectClass *klass, >> void *data) >> dc->desc = "PCI Test Device"; >> set_bit(DEVICE_CATEGORY_MISC, dc->categories); >> dc->reset = qdev_pci_testdev_reset; >> + dc->props = pci_testdev_properties; >> } >> >> static const TypeInfo pci_testdev_info = { >> >