From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A8202C4332F for ; Wed, 21 Dec 2022 01:08:12 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1p7nZp-0003iS-OV; Tue, 20 Dec 2022 20:07:22 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1p7nZL-0002tk-U2 for qemu-devel@nongnu.org; Tue, 20 Dec 2022 20:06:52 -0500 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1p7nZG-0004EK-Pd for qemu-devel@nongnu.org; Tue, 20 Dec 2022 20:06:51 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Sender:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description; bh=9SynsT3KtYwdhBUKqZkrwfrzcKDwHRkNzNMvfpp0CFs=; b=XYqBF9mYyhokXGOV3wvyol15Y7 Hb9O0oZV67TtRkHqYQrp6R9nWz+BZnnIaoSY+9TXbRi6ziNi7y0qL1w6kqX5+tYJZ3hFm0L/nXTlA RWPpx7P6AkrNjlCpKJWt2nz9Rpe+HCOFWBr6+nlUCFch6enWLBI9UtYWaPRse0wYmg/9t14W/FANY iNr18fW3t78AtOgZGLldrS2nZ7zUoYwGqTsr8A8jJXB1tZDeCKqrXmN3mFxeqUX3XNtFcMzo/jKwY YUASguz8UsNLejAG3qOCpHpQXa46rTWqySXlJZIYQlTMrpY5SYzPTBkTncjAWa1N/aJXg/Z8zwfyt Dm7ku3JQ==; Received: from i7.infradead.org ([2001:8b0:10b:1:21e:67ff:fecb:7a92]) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1p7nZ8-002Kcg-F5; Wed, 21 Dec 2022 01:06:39 +0000 Received: from dwoodhou by i7.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1p7nYw-004CMA-Jy; Wed, 21 Dec 2022 01:06:26 +0000 From: David Woodhouse To: qemu-devel@nongnu.org Cc: Paolo Bonzini , Paul Durrant , Joao Martins , Ankur Arora , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Thomas Huth , =?UTF-8?q?Alex=20Benn=C3=A9e?= , Juan Quintela , "Dr . David Alan Gilbert" , Claudio Fontana Subject: [RFC PATCH v4 16/47] i386/xen: manage and save/restore Xen guest long_mode setting Date: Wed, 21 Dec 2022 01:05:52 +0000 Message-Id: <20221221010623.1000191-17-dwmw2@infradead.org> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20221221010623.1000191-1-dwmw2@infradead.org> References: <20221221010623.1000191-1-dwmw2@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Received-SPF: none client-ip=2001:8b0:10b:1236::1; envelope-from=BATV+b12bb331c036832273ad+7059+infradead.org+dwmw2@casper.srs.infradead.org; helo=casper.infradead.org X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: David Woodhouse Xen will "latch" the guest's 32-bit or 64-bit ("long mode") setting when the guest writes the MSR to fill in the hypercall page, or when the guest sets the event channel callback in HVM_PARAM_CALLBACK_IRQ. KVM handles the former and sets the kernel's long_mode flag accordingly. The latter will be handled in userspace. Keep them in sync by noticing when a hypercall is made in a mode that doesn't match qemu's idea of the guest mode, and resyncing from the kernel. Do that same sync right before serialization too, in case the guest has set the hypercall page but hasn't yet made a system call. Signed-off-by: David Woodhouse --- hw/i386/kvm/xen_overlay.c | 65 +++++++++++++++++++++++++++++++++++++++ hw/i386/kvm/xen_overlay.h | 4 +++ target/i386/kvm/xen-emu.c | 12 ++++++++ 3 files changed, 81 insertions(+) diff --git a/hw/i386/kvm/xen_overlay.c b/hw/i386/kvm/xen_overlay.c index 331dea6b8b..7046bd55f1 100644 --- a/hw/i386/kvm/xen_overlay.c +++ b/hw/i386/kvm/xen_overlay.c @@ -44,6 +44,7 @@ struct XenOverlayState { MemoryRegion shinfo_mem; void *shinfo_ptr; uint64_t shinfo_gpa; + bool long_mode; }; struct XenOverlayState *xen_overlay_singleton; @@ -96,9 +97,21 @@ static void xen_overlay_realize(DeviceState *dev, Error **errp) s->shinfo_ptr = memory_region_get_ram_ptr(&s->shinfo_mem); s->shinfo_gpa = INVALID_GPA; + s->long_mode = false; memset(s->shinfo_ptr, 0, XEN_PAGE_SIZE); } +static int xen_overlay_pre_save(void *opaque) +{ + /* + * Fetch the kernel's idea of long_mode to avoid the race condition + * where the guest has set the hypercall page up in 64-bit mode but + * not yet made a hypercall by the time migration happens, so qemu + * hasn't yet noticed. + */ + return xen_sync_long_mode(); +} + static int xen_overlay_post_load(void *opaque, int version_id) { XenOverlayState *s = opaque; @@ -107,6 +120,9 @@ static int xen_overlay_post_load(void *opaque, int version_id) xen_overlay_map_page_locked(&s->shinfo_mem, s->shinfo_gpa); xen_overlay_set_be_shinfo(s->shinfo_gpa >> XEN_PAGE_SHIFT); } + if (s->long_mode) { + xen_set_long_mode(true); + } return 0; } @@ -121,9 +137,11 @@ static const VMStateDescription xen_overlay_vmstate = { .version_id = 1, .minimum_version_id = 1, .needed = xen_overlay_is_needed, + .pre_save = xen_overlay_pre_save, .post_load = xen_overlay_post_load, .fields = (VMStateField[]) { VMSTATE_UINT64(shinfo_gpa, XenOverlayState), + VMSTATE_BOOL(long_mode, XenOverlayState), VMSTATE_END_OF_LIST() } }; @@ -198,3 +216,50 @@ void *xen_overlay_get_shinfo_ptr(void) return s->shinfo_ptr; } + +int xen_sync_long_mode(void) +{ + int ret; + struct kvm_xen_hvm_attr xa = { + .type = KVM_XEN_ATTR_TYPE_LONG_MODE, + }; + + if (!xen_overlay_singleton) { + return -ENOENT; + } + + ret = kvm_vm_ioctl(kvm_state, KVM_XEN_HVM_GET_ATTR, &xa); + if (!ret) { + xen_overlay_singleton->long_mode = xa.u.long_mode; + } + + return ret; +} + +int xen_set_long_mode(bool long_mode) +{ + int ret; + struct kvm_xen_hvm_attr xa = { + .type = KVM_XEN_ATTR_TYPE_LONG_MODE, + .u.long_mode = long_mode, + }; + + if (!xen_overlay_singleton) { + return -ENOENT; + } + + ret = kvm_vm_ioctl(kvm_state, KVM_XEN_HVM_SET_ATTR, &xa); + if (!ret) { + xen_overlay_singleton->long_mode = xa.u.long_mode; + } + + return ret; +} + +bool xen_is_long_mode(void) +{ + if (xen_overlay_singleton) { + return xen_overlay_singleton->long_mode; + } + return false; +} diff --git a/hw/i386/kvm/xen_overlay.h b/hw/i386/kvm/xen_overlay.h index 00cff05bb0..5c46a0b036 100644 --- a/hw/i386/kvm/xen_overlay.h +++ b/hw/i386/kvm/xen_overlay.h @@ -17,4 +17,8 @@ void xen_overlay_create(void); int xen_overlay_map_shinfo_page(uint64_t gpa); void *xen_overlay_get_shinfo_ptr(void); +int xen_sync_long_mode(void); +int xen_set_long_mode(bool long_mode); +bool xen_is_long_mode(void); + #endif /* QEMU_XEN_OVERLAY_H */ diff --git a/target/i386/kvm/xen-emu.c b/target/i386/kvm/xen-emu.c index 80005ea527..80f09f33df 100644 --- a/target/i386/kvm/xen-emu.c +++ b/target/i386/kvm/xen-emu.c @@ -19,6 +19,8 @@ #include "trace.h" #include "sysemu/runstate.h" +#include "hw/i386/kvm/xen_overlay.h" + #include "standard-headers/xen/version.h" #include "standard-headers/xen/sched.h" @@ -274,6 +276,16 @@ int kvm_xen_handle_exit(X86CPU *cpu, struct kvm_xen_exit *exit) return -1; } + /* + * The kernel latches the guest 32/64 mode when the MSR is used to fill + * the hypercall page. So if we see a hypercall in a mode that doesn't + * match our own idea of the guest mode, fetch the kernel's idea of the + * "long mode" to remain in sync. + */ + if (exit->u.hcall.longmode != xen_is_long_mode()) { + xen_sync_long_mode(); + } + if (!do_kvm_xen_handle_exit(cpu, exit)) { /* * Some hypercalls will be deliberately "implemented" by returning -- 2.35.3