From: Paul Durrant <pdurrant@xxxxxxxxxx> There are four new patches in the series over what was in version 9 [1]: * KVM: xen: separate initialization of shared_info cache and content * KVM: xen: (re-)initialize shared_info if guest (32/64-bit) mode is set These deal with a missing re-initialization of shared_info if either the guest or VMM changes the 'long_mode' flag. This was discovred in testing when the guest wallclock reverted to the Unix epoch because the pvclock information in the shared_info page was not in the correct place, and so the guest read zeroes instead. * KVM: xen: don't block on pfncache locks in kvm_xen_set_evtchn_fast() * KVM: pfncache: check the need for invalidation under read lock first The first of these fixes a bug discovered when compiling the kernel with CONFIG_PROVE_RAW_LOCK_NESTING: kvm_xen_set_evtchn_fast() can be called from the callback of a HRTIMER_MODE_ABS_HARD timer and hence be executed in IRQ context. It should therefore not block on any lock. Thus two occurrences of a read_lock() are converted to a read_trylock() which kick the code down a slow-path if they fail. The second patch removes a 'false' contention on the pfncache lock that could result in taking that slow-path: the MMU notifier callback need only take a pfncache read lock; it only need take a write lock if a match is found. Apart from these new patches... * KVM: xen: split up kvm_xen_set_evtchn_fast() ... has been re-worked to (hopefully) improve readability and also validate the 'correct' vcpu_info structure depending on whether the guest is in long mode or not. [1] https://lore.kernel.org/kvm/20231122121822.1042-1-paul@xxxxxxx/ Paul Durrant (19): KVM: pfncache: Add a map helper function KVM: pfncache: remove unnecessary exports KVM: xen: mark guest pages dirty with the pfncache lock held KVM: pfncache: add a mark-dirty helper KVM: pfncache: remove KVM_GUEST_USES_PFN usage KVM: pfncache: stop open-coding offset_in_page() KVM: pfncache: include page offset in uhva and use it consistently KVM: pfncache: allow a cache to be activated with a fixed (userspace) HVA KVM: xen: separate initialization of shared_info cache and content KVM: xen: (re-)initialize shared_info if guest (32/64-bit) mode is set KVM: xen: allow shared_info to be mapped by fixed HVA KVM: xen: allow vcpu_info to be mapped by fixed HVA KVM: selftests / xen: map shared_info using HVA rather than GFN KVM: selftests / xen: re-map vcpu_info using HVA rather than GPA KVM: xen: advertize the KVM_XEN_HVM_CONFIG_SHARED_INFO_HVA capability KVM: xen: split up kvm_xen_set_evtchn_fast() KVM: xen: don't block on pfncache locks in kvm_xen_set_evtchn_fast() KVM: pfncache: check the need for invalidation under read lock first KVM: xen: allow vcpu_info content to be 'safely' copied Documentation/virt/kvm/api.rst | 53 ++- arch/x86/kvm/x86.c | 7 +- arch/x86/kvm/xen.c | 358 +++++++++++------- include/linux/kvm_host.h | 40 +- include/linux/kvm_types.h | 8 - include/uapi/linux/kvm.h | 9 +- .../selftests/kvm/x86_64/xen_shinfo_test.c | 59 ++- virt/kvm/pfncache.c | 185 ++++----- 8 files changed, 461 insertions(+), 258 deletions(-) base-commit: 1ab097653e4dd8d23272d028a61352c23486fd4a -- 2.39.2
