On Linux systems hypercall buffers in user memory are allocated with MAP_LOCKED attribute. Unfortunately that doesn't mean that the buffer will always be accessible by the hypervisor, as the kernel might set the PTE for the buffer to invalid or read only for short periods of time, e.g. due to page migration or compaction.
This results in highly sporadic -EFAULT for hypercalls issued by Xen tools. Fix this problem by using a new device node of the Linux privcmd driver for allocating hypercall buffers. Add a fallback in case the Linux kernel doesn't support that new device node by repeating the getpageframeinfo3 hypercall which until now has been the only one to be observed suffering from that problem. This series is meant to be included in 4.11, so it can right away have my: Release-acked-by: Juergen Gross <jgr...@suse.com> Juergen Gross (3): tools/libxencall: use hypercall buffer device if available tools/libxencalls: add new function to query hypercall buffer safety tools/libxc: retry hypercall in case of EFAULT tools/libs/call/Makefile | 2 +- tools/libs/call/core.c | 8 +++++++- tools/libs/call/freebsd.c | 5 +++++ tools/libs/call/include/xencall.h | 7 +++++++ tools/libs/call/libxencall.map | 5 +++++ tools/libs/call/linux.c | 34 ++++++++++++++++++++++++++++++++-- tools/libs/call/minios.c | 5 +++++ tools/libs/call/netbsd.c | 5 +++++ tools/libs/call/private.h | 1 + tools/libs/call/solaris.c | 5 +++++ tools/libxc/xc_private.c | 2 +- tools/libxc/xc_private.h | 24 +++++++++++++++++++++--- 12 files changed, 95 insertions(+), 8 deletions(-) -- 2.13.7 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
