From aff92b828647839b956dfa647a18b3ce10058e6a Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Fri, 26 Jun 2020 09:22:30 +0200 Subject: vfio: Convert to ram_block_discard_disable() VFIO is (except devices without a physical IOMMU or some mediated devices) incompatible with discarding of RAM. The kernel will pin basically all VM memory. Let's convert to ram_block_discard_disable(), which can now fail, in contrast to qemu_balloon_inhibit(). Leave "x-balloon-allowed" named as it is for now. Reviewed-by: Tony Krowiak Acked-by: Cornelia Huck Cc: Cornelia Huck Cc: Alex Williamson Cc: Christian Borntraeger Cc: Tony Krowiak Cc: Halil Pasic Cc: Pierre Morel Cc: Eric Farman Signed-off-by: David Hildenbrand Message-Id: <20200626072248.78761-4-david@redhat.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/vfio/ap.c | 8 ++++---- hw/vfio/ccw.c | 11 ++++++----- hw/vfio/common.c | 53 +++++++++++++++++++++++++++++------------------------ hw/vfio/pci.c | 6 +++--- 4 files changed, 42 insertions(+), 36 deletions(-) (limited to 'hw/vfio') diff --git a/hw/vfio/ap.c b/hw/vfio/ap.c index 95564c17ed..b9330a8e6f 100644 --- a/hw/vfio/ap.c +++ b/hw/vfio/ap.c @@ -105,12 +105,12 @@ static void vfio_ap_realize(DeviceState *dev, Error **errp) vapdev->vdev.dev = dev; /* - * vfio-ap devices operate in a way compatible with - * memory ballooning, as no pages are pinned in the host. + * vfio-ap devices operate in a way compatible with discarding of + * memory in RAM blocks, as no pages are pinned in the host. * This needs to be set before vfio_get_device() for vfio common to - * handle the balloon inhibitor. + * handle ram_block_discard_disable(). */ - vapdev->vdev.balloon_allowed = true; + vapdev->vdev.ram_block_discard_allowed = true; ret = vfio_get_device(vfio_group, mdevid, &vapdev->vdev, errp); if (ret) { diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c index 06e69d7066..ff7f369779 100644 --- a/hw/vfio/ccw.c +++ b/hw/vfio/ccw.c @@ -574,12 +574,13 @@ static void vfio_ccw_get_device(VFIOGroup *group, VFIOCCWDevice *vcdev, /* * All vfio-ccw devices are believed to operate in a way compatible with - * memory ballooning, ie. pages pinned in the host are in the current - * working set of the guest driver and therefore never overlap with pages - * available to the guest balloon driver. This needs to be set before - * vfio_get_device() for vfio common to handle the balloon inhibitor. + * discarding of memory in RAM blocks, ie. pages pinned in the host are + * in the current working set of the guest driver and therefore never + * overlap e.g., with pages available to the guest balloon driver. This + * needs to be set before vfio_get_device() for vfio common to handle + * ram_block_discard_disable(). */ - vcdev->vdev.balloon_allowed = true; + vcdev->vdev.ram_block_discard_allowed = true; if (vfio_get_device(group, vcdev->cdev.mdevid, &vcdev->vdev, errp)) { goto out_err; diff --git a/hw/vfio/common.c b/hw/vfio/common.c index 0b3593b3c0..33357140b8 100644 --- a/hw/vfio/common.c +++ b/hw/vfio/common.c @@ -33,7 +33,6 @@ #include "qemu/error-report.h" #include "qemu/main-loop.h" #include "qemu/range.h" -#include "sysemu/balloon.h" #include "sysemu/kvm.h" #include "sysemu/reset.h" #include "trace.h" @@ -1215,31 +1214,36 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as, space = vfio_get_address_space(as); /* - * VFIO is currently incompatible with memory ballooning insofar as the + * VFIO is currently incompatible with discarding of RAM insofar as the * madvise to purge (zap) the page from QEMU's address space does not * interact with the memory API and therefore leaves stale virtual to * physical mappings in the IOMMU if the page was previously pinned. We - * therefore add a balloon inhibit for each group added to a container, + * therefore set discarding broken for each group added to a container, * whether the container is used individually or shared. This provides * us with options to allow devices within a group to opt-in and allow - * ballooning, so long as it is done consistently for a group (for instance + * discarding, so long as it is done consistently for a group (for instance * if the device is an mdev device where it is known that the host vendor * driver will never pin pages outside of the working set of the guest - * driver, which would thus not be ballooning candidates). + * driver, which would thus not be discarding candidates). * * The first opportunity to induce pinning occurs here where we attempt to * attach the group to existing containers within the AddressSpace. If any - * pages are already zapped from the virtual address space, such as from a - * previous ballooning opt-in, new pinning will cause valid mappings to be + * pages are already zapped from the virtual address space, such as from + * previous discards, new pinning will cause valid mappings to be * re-established. Likewise, when the overall MemoryListener for a new * container is registered, a replay of mappings within the AddressSpace * will occur, re-establishing any previously zapped pages as well. * - * NB. Balloon inhibiting does not currently block operation of the - * balloon driver or revoke previously pinned pages, it only prevents - * calling madvise to modify the virtual mapping of ballooned pages. + * Especially virtio-balloon is currently only prevented from discarding + * new memory, it will not yet set ram_block_discard_set_required() and + * therefore, neither stops us here or deals with the sudden memory + * consumption of inflated memory. */ - qemu_balloon_inhibit(true); + ret = ram_block_discard_disable(true); + if (ret) { + error_setg_errno(errp, -ret, "Cannot set discarding of RAM broken"); + return ret; + } QLIST_FOREACH(container, &space->containers, next) { if (!ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &container->fd)) { @@ -1405,7 +1409,7 @@ close_fd_exit: close(fd); put_space_exit: - qemu_balloon_inhibit(false); + ram_block_discard_disable(false); vfio_put_address_space(space); return ret; @@ -1526,8 +1530,8 @@ void vfio_put_group(VFIOGroup *group) return; } - if (!group->balloon_allowed) { - qemu_balloon_inhibit(false); + if (!group->ram_block_discard_allowed) { + ram_block_discard_disable(false); } vfio_kvm_device_del_group(group); vfio_disconnect_container(group); @@ -1565,22 +1569,23 @@ int vfio_get_device(VFIOGroup *group, const char *name, } /* - * Clear the balloon inhibitor for this group if the driver knows the - * device operates compatibly with ballooning. Setting must be consistent - * per group, but since compatibility is really only possible with mdev - * currently, we expect singleton groups. + * Set discarding of RAM as not broken for this group if the driver knows + * the device operates compatibly with discarding. Setting must be + * consistent per group, but since compatibility is really only possible + * with mdev currently, we expect singleton groups. */ - if (vbasedev->balloon_allowed != group->balloon_allowed) { + if (vbasedev->ram_block_discard_allowed != + group->ram_block_discard_allowed) { if (!QLIST_EMPTY(&group->device_list)) { - error_setg(errp, - "Inconsistent device balloon setting within group"); + error_setg(errp, "Inconsistent setting of support for discarding " + "RAM (e.g., balloon) within group"); close(fd); return -1; } - if (!group->balloon_allowed) { - group->balloon_allowed = true; - qemu_balloon_inhibit(false); + if (!group->ram_block_discard_allowed) { + group->ram_block_discard_allowed = true; + ram_block_discard_disable(false); } } diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c index 6838bcc4b3..d020ea9f82 100644 --- a/hw/vfio/pci.c +++ b/hw/vfio/pci.c @@ -2789,7 +2789,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp) } /* - * Mediated devices *might* operate compatibly with memory ballooning, but + * Mediated devices *might* operate compatibly with discarding of RAM, but * we cannot know for certain, it depends on whether the mdev vendor driver * stays in sync with the active working set of the guest driver. Prevent * the x-balloon-allowed option unless this is minimally an mdev device. @@ -2802,7 +2802,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp) trace_vfio_mdev(vdev->vbasedev.name, is_mdev); - if (vdev->vbasedev.balloon_allowed && !is_mdev) { + if (vdev->vbasedev.ram_block_discard_allowed && !is_mdev) { error_setg(errp, "x-balloon-allowed only potentially compatible " "with mdev devices"); vfio_put_group(group); @@ -3156,7 +3156,7 @@ static Property vfio_pci_dev_properties[] = { VFIO_FEATURE_ENABLE_IGD_OPREGION_BIT, false), DEFINE_PROP_BOOL("x-no-mmap", VFIOPCIDevice, vbasedev.no_mmap, false), DEFINE_PROP_BOOL("x-balloon-allowed", VFIOPCIDevice, - vbasedev.balloon_allowed, false), + vbasedev.ram_block_discard_allowed, false), DEFINE_PROP_BOOL("x-no-kvm-intx", VFIOPCIDevice, no_kvm_intx, false), DEFINE_PROP_BOOL("x-no-kvm-msi", VFIOPCIDevice, no_kvm_msi, false), DEFINE_PROP_BOOL("x-no-kvm-msix", VFIOPCIDevice, no_kvm_msix, false), -- cgit v1.2.3-55-g7522