From patchwork Mon Dec 4 14:43:15 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Durrant X-Patchwork-Id: 750263 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=xen.org header.i=@xen.org header.b="aTxlUtH0" Received: from mail.xenproject.org (mail.xenproject.org [104.130.215.37]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 386C91733 for ; Mon, 4 Dec 2023 07:02:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:MIME-Version:Message-Id:Date: Subject:To:From; bh=EhQi3onL9GpEqJYUYdTVsT5Q2f0NwXP08T0ndFJ/c7M=; b=aTxlUtH06 VlLvCE9ceDi8kZAqPwZofP2Wp9wkcSYAWChi0ExMNgvIzt+1sbkygWUSu/qkm5fD6fdnFAwM0tiy6 Nr9uCHWMmqY3npFk8DCYOgKus5MJ22786Ii2KZJghUQN9Jea+POrOkaDZiYFt0gn/n9Xw28R3fI49 28d9t3Xs=; Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1rAAAs-0003d8-1y; Mon, 04 Dec 2023 14:43:54 +0000 Received: from 54-240-197-231.amazon.com ([54.240.197.231] helo=REM-PW02S00X.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1rAAAr-00088g-Ng; Mon, 04 Dec 2023 14:43:53 +0000 From: Paul Durrant To: Paolo Bonzini , Jonathan Corbet , Sean Christopherson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , David Woodhouse , Paul Durrant , Shuah Khan , kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH v10 00/19] KVM: xen: update shared_info and vcpu_info handling Date: Mon, 4 Dec 2023 14:43:15 +0000 Message-Id: <20231204144334.910-1-paul@xen.org> X-Mailer: git-send-email 2.39.2 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Paul Durrant 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@xen.org/ 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