kernel/linux.git/drivers/xen/privcmd.c, branch v6.12.80

xen/privcmd: unregister xenstore notifier on module exit

2026-04-02T11:09:54+00:00

[ Upstream commit cd7e1fef5a1ca1c4fcd232211962ac2395601636 ] Commit 453b8fb68f36 ("xen/privcmd: restrict usage in unprivileged domU") added a xenstore notifier to defer setting the restriction target until Xenstore is ready. XEN_PRIVCMD can be built as a module, but privcmd_exit() leaves that notifier behind. Balance the notifier lifecycle by unregistering it on module exit. This is harmless even if xenstore was already ready at registration time and the notifier was never queued on the chain. Fixes: 453b8fb68f3641fe ("xen/privcmd: restrict usage in unprivileged domU") Signed-off-by: GuoHan Zhao Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross Message-ID: <20260325120246.252899-1-zhaoguohan@kylinos.cn> Signed-off-by: Sasha Levin

xen/privcmd: add boot control for restricted usage in domU

2026-03-25T10:08:57+00:00

commit 1613462be621ad5103ec338a7b0ca0746ec4e5f1 upstream. When running in an unprivileged domU under Xen, the privcmd driver is restricted to allow only hypercalls against a target domain, for which the current domU is acting as a device model. Add a boot parameter "unrestricted" to allow all hypercalls (the hypervisor will still refuse destructive hypercalls affecting other guests). Make this new parameter effective only in case the domU wasn't started using secure boot, as otherwise hypercalls targeting the domU itself might result in violating the secure boot functionality. This is achieved by adding another lockdown reason, which can be tested to not being set when applying the "unrestricted" option. This is part of XSA-482 Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman

xen/privcmd: restrict usage in unprivileged domU

2026-03-25T10:08:57+00:00

commit 453b8fb68f3641fea970db88b7d9a153ed2a37e8 upstream. The Xen privcmd driver allows to issue arbitrary hypercalls from user space processes. This is normally no problem, as access is usually limited to root and the hypervisor will deny any hypercalls affecting other domains. In case the guest is booted using secure boot, however, the privcmd driver would be enabling a root user process to modify e.g. kernel memory contents, thus breaking the secure boot feature. The only known case where an unprivileged domU is really needing to use the privcmd driver is the case when it is acting as the device model for another guest. In this case all hypercalls issued via the privcmd driver will target that other guest. Fortunately the privcmd driver can already be locked down to allow only hypercalls targeting a specific domain, but this mode can be activated from user land only today. The target domain can be obtained from Xenstore, so when not running in dom0 restrict the privcmd driver to that target domain from the beginning, resolving the potential problem of breaking secure boot. This is XSA-482 Reported-by: Teddy Astie Fixes: 1c5de1939c20 ("xen: add privcmd driver") Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman

xen: Remove dependency between pciback and privcmd

2024-10-18T09:59:04+00:00

Commit 2fae6bb7be32 ("xen/privcmd: Add new syscall to get gsi from dev") adds a weak reverse dependency to the config XEN_PRIVCMD definition, that dependency causes xen-privcmd can't be loaded on domU, because dependent xen-pciback isn't always be loaded successfully on domU. To solve above problem, remove that dependency, and do not call pcistub_get_gsi_from_sbdf() directly, instead add a hook in drivers/xen/apci.c, xen-pciback register the real call function, then in privcmd_ioctl_pcidev_get_gsi call that hook. Fixes: 2fae6bb7be32 ("xen/privcmd: Add new syscall to get gsi from dev") Reported-by: Marek Marczykowski-Górecki Signed-off-by: Jiqian Chen Reviewed-by: Juergen Gross Message-ID: <20241012084537.1543059-1-Jiqian.Chen@amd.com> Signed-off-by: Juergen Gross

Merge tag 'for-linus-6.12-rc1a-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

2024-09-27T16:55:30+00:00

Pull more xen updates from Juergen Gross: "A second round of Xen related changes and features: - a small fix of the xen-pciback driver for a warning issued by sparse - support PCI passthrough when using a PVH dom0 - enable loading the kernel in PVH mode at arbitrary addresses, avoiding conflicts with the memory map when running as a Xen dom0 using the host memory layout" * tag 'for-linus-6.12-rc1a-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: x86/pvh: Add 64bit relocation page tables x86/kernel: Move page table macros to header x86/pvh: Set phys_base when calling xen_prepare_pvh() x86/pvh: Make PVH entrypoint PIC for x86-64 xen: sync elfnote.h from xen tree xen/pciback: fix cast to restricted pci_ers_result_t and pci_power_t xen/privcmd: Add new syscall to get gsi from dev xen/pvh: Setup gsi for passthrough device xen/pci: Add a function to reset device for xen

xen/privcmd: Add new syscall to get gsi from dev

2024-09-25T07:54:55+00:00

On PVH dom0, when passthrough a device to domU, QEMU and xl tools want to use gsi number to do pirq mapping, see QEMU code xen_pt_realize->xc_physdev_map_pirq, and xl code pci_add_dm_done->xc_physdev_map_pirq, but in current codes, the gsi number is got from file /sys/bus/pci/devices//irq, that is wrong, because irq is not equal with gsi, they are in different spaces, so pirq mapping fails. And in current linux codes, there is no method to get gsi for userspace. For above purpose, record gsi of pcistub devices when init pcistub and add a new syscall into privcmd to let userspace can get gsi when they have a need. Signed-off-by: Jiqian Chen Signed-off-by: Huang Rui Signed-off-by: Jiqian Chen Reviewed-by: Stefano Stabellini Message-ID: <20240924061437.2636766-4-Jiqian.Chen@amd.com> Signed-off-by: Juergen Gross

introduce fd_file(), convert all accessors to it.

2024-08-13T02:00:43+00:00

For any changes of struct fd representation we need to turn existing accesses to fields into calls of wrappers. Accesses to struct fd::flags are very few (3 in linux/file.h, 1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in explicit initializers). Those can be dealt with in the commit converting to new layout; accesses to struct fd::file are too many for that. This commit converts (almost) all of f.file to fd_file(f). It's not entirely mechanical ('file' is used as a member name more than just in struct fd) and it does not even attempt to distinguish the uses in pointer context from those in boolean context; the latter will be eventually turned into a separate helper (fd_empty()). NOTE: mass conversion to fd_empty(), tempting as it might be, is a bad idea; better do that piecewise in commit that convert from fdget...() to CLASS(...). [conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c caught by git; fs/stat.c one got caught by git grep] [fs/xattr.c conflict] Reviewed-by: Christian Brauner Signed-off-by: Al Viro

xen: privcmd: Fix possible access to a freed kirqfd instance

2024-07-02T10:23:42+00:00

Nothing prevents simultaneous ioctl calls to privcmd_irqfd_assign() and privcmd_irqfd_deassign(). If that happens, it is possible that a kirqfd created and added to the irqfds_list by privcmd_irqfd_assign() may get removed by another thread executing privcmd_irqfd_deassign(), while the former is still using it after dropping the locks. This can lead to a situation where an already freed kirqfd instance may be accessed and cause kernel oops. Use SRCU locking to prevent the same, as is done for the KVM implementation for irqfds. Reported-by: Al Viro Suggested-by: Paolo Bonzini Signed-off-by: Viresh Kumar Reviewed-by: Juergen Gross Link: https://lore.kernel.org/r/9e884af1f1f842eacbb7afc5672c8feb4dea7f3f.1718703669.git.viresh.kumar@linaro.org Signed-off-by: Juergen Gross

xen: privcmd: Switch from mutex to spinlock for irqfds

2024-07-02T10:23:39+00:00

irqfd_wakeup() gets EPOLLHUP, when it is called by eventfd_release() by way of wake_up_poll(&ctx->wqh, EPOLLHUP), which gets called under spin_lock_irqsave(). We can't use a mutex here as it will lead to a deadlock. Fix it by switching over to a spin lock. Reported-by: Al Viro Signed-off-by: Viresh Kumar Reviewed-by: Juergen Gross Link: https://lore.kernel.org/r/a66d7a7a9001424d432f52a9fc3931a1f345464f.1718703669.git.viresh.kumar@linaro.org Signed-off-by: Juergen Gross

xen: add missing MODULE_DESCRIPTION() macros

2024-07-02T07:41:46+00:00

With ARCH=x86, make allmodconfig && make W=1 C=1 reports: WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/xen/xen-pciback/xen-pciback.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/xen/xen-evtchn.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/xen/xen-privcmd.o Add the missing invocations of the MODULE_DESCRIPTION() macro. Signed-off-by: Jeff Johnson Reviewed-by: Juergen Gross Link: https://lore.kernel.org/r/20240611-md-drivers-xen-v1-1-1eb677364ca6@quicinc.com Signed-off-by: Juergen Gross