From nobody Tue Feb 10 09:10:38 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1673360290869947.7305666520639; Tue, 10 Jan 2023 06:18:10 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pFDfb-0001O0-N9; Tue, 10 Jan 2023 07:24:00 -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 1pFDcw-00079n-FP for qemu-devel@nongnu.org; Tue, 10 Jan 2023 07:21:15 -0500 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pFDcr-0000U3-VB for qemu-devel@nongnu.org; Tue, 10 Jan 2023 07:21:14 -0500 Received: from i7.infradead.org ([2001:8b0:10b:1:21e:67ff:fecb:7a92]) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1pFDcM-0037tq-2F; Tue, 10 Jan 2023 12:20:50 +0000 Received: from dwoodhou by i7.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pFDcT-006Ygp-OQ; Tue, 10 Jan 2023 12:20:45 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=mAwF0Xdtkw/YWSfzxAZEktjLvXD79n/Djs1yLctiAnQ=; b=byzRjK3+M3KmLgndXXHUu0T4Lz F5hOnLuv6jvsT5y08pxnhZE1IF2oMuTcVQjioFJE7/0MoXwvgTyb1CLAfiEn5d9l1R+xiBKoxusiZ ChJ12We3AwFU3tSYYNY2g8WVpd08nMZxkwJEgwQ8Oxl0E7GzQ+vVLh6gic7pXk086qO5iXiY7ok6m SCVA9y6CIghetMUhPVwtWChx18RzfXGPogMNaVr+HCs31zf8zjrRk1KlYYQAy9yoBQw3Vfe40Mal/ f8/Ll5UikEExlmjTjtM8BvIs1fBVGefgHfFQV/iv6jwaSWJocOv04ijRppQq3lDkKSA/Ew9M/6Fx0 ilxFW8nA==; 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 , Julien Grall Subject: [PATCH v6 51/51] hw/xen: Add basic ring handling to xenstore Date: Tue, 10 Jan 2023 12:20:42 +0000 Message-Id: <20230110122042.1562155-52-dwmw2@infradead.org> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230110122042.1562155-1-dwmw2@infradead.org> References: <20230110122042.1562155-1-dwmw2@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-SRS-Rewrite: SMTP reverse-path rewritten from by desiato.infradead.org. See http://www.infradead.org/rpr.html Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: none client-ip=2001:8b0:10b:1:d65d:64ff:fe57:4e05; envelope-from=BATV+6ce08bad6b360d6d5e23+7079+infradead.org+dwmw2@desiato.srs.infradead.org; helo=desiato.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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZM-MESSAGEID: 1673360291505100001 Content-Type: text/plain; charset="utf-8" From: David Woodhouse Extract requests, return ENOSYS to all of them. This is enough to allow older Linux guests to boot, as they need *something* back but it doesn't matter much what. In the first instance we're likely to wire this up over a UNIX socket to an actual xenstored implementation, but in the fullness of time it would be nice to have a fully single-tenant "virtual" xenstore within qemu. Signed-off-by: David Woodhouse --- hw/i386/kvm/xen_xenstore.c | 223 ++++++++++++++++++++++++++++++++++++- 1 file changed, 220 insertions(+), 3 deletions(-) diff --git a/hw/i386/kvm/xen_xenstore.c b/hw/i386/kvm/xen_xenstore.c index bb3346f4e3..6369e29f59 100644 --- a/hw/i386/kvm/xen_xenstore.c +++ b/hw/i386/kvm/xen_xenstore.c @@ -188,18 +188,235 @@ uint16_t xen_xenstore_get_port(void) return s->guest_port; } =20 +static bool req_pending(XenXenstoreState *s) +{ + struct xsd_sockmsg *req =3D (struct xsd_sockmsg *)s->req_data; + + return s->req_offset =3D=3D XENSTORE_HEADER_SIZE + req->len; +} + +static void reset_req(XenXenstoreState *s) +{ + memset(s->req_data, 0, sizeof(s->req_data)); + s->req_offset =3D 0; +} + +static void reset_rsp(XenXenstoreState *s) +{ + s->rsp_pending =3D false; + + memset(s->rsp_data, 0, sizeof(s->rsp_data)); + s->rsp_offset =3D 0; +} + +static void process_req(XenXenstoreState *s) +{ + struct xsd_sockmsg *req =3D (struct xsd_sockmsg *)s->req_data; + struct xsd_sockmsg *rsp =3D (struct xsd_sockmsg *)s->rsp_data; + const char enosys[] =3D "ENOSYS"; + + assert(req_pending(s)); + assert(!s->rsp_pending); + + rsp->type =3D XS_ERROR; + rsp->req_id =3D req->req_id; + rsp->tx_id =3D req->tx_id; + rsp->len =3D sizeof(enosys); + memcpy((void *)&rsp[1], enosys, sizeof(enosys)); + + s->rsp_pending =3D true; + reset_req(s); +} + +static unsigned int copy_from_ring(XenXenstoreState *s, uint8_t *ptr, unsi= gned int len) +{ + if (!len) + return 0; + + XENSTORE_RING_IDX prod =3D qatomic_read(&s->xs->req_prod); + XENSTORE_RING_IDX cons =3D qatomic_read(&s->xs->req_cons); + unsigned int copied =3D 0; + + smp_mb(); + + while (len) { + unsigned int avail =3D prod - cons; + unsigned int offset =3D MASK_XENSTORE_IDX(cons); + unsigned int copylen =3D avail; + + if (avail > XENSTORE_RING_SIZE) { + error_report("XenStore ring handling error"); + s->fatal_error =3D true; + break; + } else if (avail =3D=3D 0) + break; + + if (copylen > len) { + copylen =3D len; + } + if (copylen > XENSTORE_RING_SIZE - offset) { + copylen =3D XENSTORE_RING_SIZE - offset; + } + + memcpy(ptr, &s->xs->req[offset], copylen); + copied +=3D copylen; + + ptr +=3D copylen; + len -=3D copylen; + + cons +=3D copylen; + } + + smp_mb(); + + qatomic_set(&s->xs->req_cons, cons); + + return copied; +} + +static unsigned int copy_to_ring(XenXenstoreState *s, uint8_t *ptr, unsign= ed int len) +{ + if (!len) + return 0; + + XENSTORE_RING_IDX cons =3D qatomic_read(&s->xs->rsp_cons); + XENSTORE_RING_IDX prod =3D qatomic_read(&s->xs->rsp_prod); + unsigned int copied =3D 0; + + smp_mb(); + + while (len) { + unsigned int avail =3D cons + XENSTORE_RING_SIZE - prod; + unsigned int offset =3D MASK_XENSTORE_IDX(prod); + unsigned int copylen =3D len; + + if (avail > XENSTORE_RING_SIZE) { + error_report("XenStore ring handling error"); + s->fatal_error =3D true; + break; + } else if (avail =3D=3D 0) + break; + + if (copylen > avail) { + copylen =3D avail; + } + if (copylen > XENSTORE_RING_SIZE - offset) { + copylen =3D XENSTORE_RING_SIZE - offset; + } + + + memcpy(&s->xs->rsp[offset], ptr, copylen); + copied +=3D copylen; + + ptr +=3D copylen; + len -=3D copylen; + + prod +=3D copylen; + } + + smp_mb(); + + qatomic_set(&s->xs->rsp_prod, prod); + + return copied; +} + +static unsigned int get_req(XenXenstoreState *s) +{ + unsigned int copied =3D 0; + + if (s->fatal_error) + return 0; + + assert(!req_pending(s)); + + if (s->req_offset < XENSTORE_HEADER_SIZE) { + void *ptr =3D s->req_data + s->req_offset; + unsigned int len =3D XENSTORE_HEADER_SIZE; + unsigned int copylen =3D copy_from_ring(s, ptr, len); + + copied +=3D copylen; + s->req_offset +=3D copylen; + } + + if (s->req_offset >=3D XENSTORE_HEADER_SIZE) { + struct xsd_sockmsg *req =3D (struct xsd_sockmsg *)s->req_data; + + if (req->len > (uint32_t)XENSTORE_PAYLOAD_MAX) { + error_report("Illegal XenStore request"); + s->fatal_error =3D true; + return 0; + } + + void *ptr =3D s->req_data + s->req_offset; + unsigned int len =3D XENSTORE_HEADER_SIZE + req->len - s->req_offs= et; + unsigned int copylen =3D copy_from_ring(s, ptr, len); + + copied +=3D copylen; + s->req_offset +=3D copylen; + } + + return copied; +} + +static unsigned int put_rsp(XenXenstoreState *s) +{ + if (s->fatal_error) + return 0; + + assert(s->rsp_pending); + + struct xsd_sockmsg *rsp =3D (struct xsd_sockmsg *)s->rsp_data; + assert(s->rsp_offset < XENSTORE_HEADER_SIZE + rsp->len); + + void *ptr =3D s->rsp_data + s->rsp_offset; + unsigned int len =3D XENSTORE_HEADER_SIZE + rsp->len - s->rsp_offset; + unsigned int copylen =3D copy_to_ring(s, ptr, len); + + s->rsp_offset +=3D copylen; + + /* Have we produced a complete response? */ + if (s->rsp_offset =3D=3D XENSTORE_HEADER_SIZE + rsp->len) + reset_rsp(s); + + return copylen; +} + static void xen_xenstore_event(void *opaque) { XenXenstoreState *s =3D opaque; evtchn_port_t port =3D xen_be_evtchn_pending(s->eh); + unsigned int copied_to, copied_from; + bool processed, notify =3D false; + if (port !=3D s->be_port) { return; } - printf("xenstore event\n"); + /* We know this is a no-op. */ xen_be_evtchn_unmask(s->eh, port); - qemu_hexdump(stdout, "", s->xs, sizeof(*s->xs)); - xen_be_evtchn_notify(s->eh, s->be_port); + + do { + copied_to =3D copied_from =3D 0; + processed =3D false; + + if (s->rsp_pending) + copied_to =3D put_rsp(s); + + if (!req_pending(s)) + copied_from =3D get_req(s); + + if (req_pending(s) && !s->rsp_pending) { + process_req(s); + processed =3D true; + } + + notify |=3D copied_to || copied_from; + } while (copied_to || copied_from || processed); + + if (notify) { + xen_be_evtchn_notify(s->eh, s->be_port); + } } =20 static void alloc_guest_port(XenXenstoreState *s) --=20 2.35.3