From nobody Tue Feb 10 06:26:33 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; helo=lists.xenproject.org; Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org ARC-Seal: i=1; a=rsa-sha256; t=1757365949; cv=none; d=zohomail.com; s=zohoarc; b=g8K1mZeneRyhga3ryIgOD2BQuxqWwKXoa/MudK9Hpc5HRwAEifF2WBeCXvNXVpOxhmF9zgboekNMoZXVmSaJGJVXS91FYbuqaW4zceSVSsC2kl+MMaeXbAeGdz+0LdJYTod6XBnH9bgLpjhqxWn1xdV1k7TuBUjKGr0iD8UKORA= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1757365949; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=UpqDmrURqhicTlP+xGJnrT1Wd61lJrVuEW9MZuV9LUw=; b=HL2Pn+QDJLiddYw5gZOIwYSz4MMigL/67sQboD7T0pxkxezCsZ+niiy5J4HeFONd+Z3pxbTp5HLa79qImLu8fRbWrXfovmmk2woAi2nnrfX9dY8SLGd2QTTea9VbUFrav4Ee+l84BdEtgFWz3Io/4P09/CTYPFGmyfb7vx+fQ9c= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Return-Path: Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) by mx.zohomail.com with SMTPS id 1757365949301653.739543520829; Mon, 8 Sep 2025 14:12:29 -0700 (PDT) Received: from list by lists.xenproject.org with outflank-mailman.1115539.1462131 (Exim 4.92) (envelope-from ) id 1uvj9b-0000Mq-Sq; Mon, 08 Sep 2025 21:11:59 +0000 Received: by outflank-mailman (output) from mailman id 1115539.1462131; Mon, 08 Sep 2025 21:11:59 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1uvj9b-0000Kl-Mq; Mon, 08 Sep 2025 21:11:59 +0000 Received: by outflank-mailman (input) for mailman id 1115539; Mon, 08 Sep 2025 21:11:59 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1uvj9a-0000E8-Vi for xen-devel@lists.xenproject.org; Mon, 08 Sep 2025 21:11:58 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.96) (envelope-from ) id 1uvj9a-000FTE-26; Mon, 08 Sep 2025 21:11:58 +0000 Received: from [19.12.91.86] (helo=localhost) by xenbits.xenproject.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1uvj9a-000gMH-2K; Mon, 08 Sep 2025 21:11:58 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:MIME-Version:References: In-Reply-To:Message-ID:Date:Subject:Cc:To:From; bh=UpqDmrURqhicTlP+xGJnrT1Wd61lJrVuEW9MZuV9LUw=; b=QJ+W5RoOargplJeMWgu+XCccUz wZJBB6qyLmwA6PakBbMOh8500+D+mgMfVMPDgHPZa+OZ+1SGo2fo3OIGrZuQUuI5j7qmTXKN26yCk 91RDoRYIJxLN6G66S7CZlRJkXeYy3HRRx+GeUjjYcAXXbOLUFQ8ld2hXjiPr35WrAJP8=; From: dmukhin@xen.org To: xen-devel@lists.xenproject.org Cc: andrew.cooper3@citrix.com, anthony.perard@vates.tech, jbeulich@suse.com, julien@xen.org, michal.orzel@amd.com, roger.pau@citrix.com, sstabellini@kernel.org, dmukhin@ford.com Subject: [PATCH v7 06/16] emul/ns16x50: implement IER/IIR registers Date: Mon, 8 Sep 2025 14:11:39 -0700 Message-ID: <20250908211149.279143-7-dmukhin@ford.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250908211149.279143-1-dmukhin@ford.com> References: <20250908211149.279143-1-dmukhin@ford.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @xen.org) X-ZM-MESSAGEID: 1757365950138116600 Content-Type: text/plain; charset="utf-8" From: Denis Mukhin =20 Add interrupt enable register emulation (IER) and interrupt identity reason (IIR) register emulation to the I/O port handler. Also add routines for asserting/deasserting the virtual ns16x50 interrupt line as a dependent on IIR code. vPIC case is implemented (HVM), vIOAPIC case is stubbed out (for follow on PVH). Poke ns16x50_irq_check() on every I/O register access because the emulator does not have clock emulation anyway (e.g. for baud rate emulation). Signed-off-by: Denis Mukhin --- Changes since v6: - removed asserts for !has_vpic() paths --- xen/common/emul/vuart/ns16x50.c | 138 ++++++++++++++++++++++++++++++++ 1 file changed, 138 insertions(+) diff --git a/xen/common/emul/vuart/ns16x50.c b/xen/common/emul/vuart/ns16x5= 0.c index 5643ef4cc01e..664d799ddaee 100644 --- a/xen/common/emul/vuart/ns16x50.c +++ b/xen/common/emul/vuart/ns16x50.c @@ -90,6 +90,124 @@ static uint8_t ns16x50_dlab_get(const struct vuart_ns16= x50 *vdev) return 0; } =20 +static bool cf_check ns16x50_iir_check_lsi(const struct vuart_ns16x50 *vde= v) +{ + return false; +} + +static bool cf_check ns16x50_iir_check_rda(const struct vuart_ns16x50 *vde= v) +{ + return false; +} + +static bool cf_check ns16x50_iir_check_thr(const struct vuart_ns16x50 *vde= v) +{ + return false; +} + +static bool cf_check ns16x50_iir_check_msi(const struct vuart_ns16x50 *vde= v) +{ + return false; +} + +/* + * Get the interrupt identity reason. + * + * IIR is re-calculated once called, because ns16x50 always reports high + * priority events first. + */ +static uint8_t ns16x50_iir_get(const struct vuart_ns16x50 *vdev) +{ + /* + * Interrupt identity reasons by priority. + * NB: high priority are at lower indexes below. + */ + static const struct { + bool (*check)(const struct vuart_ns16x50 *vdev); + uint8_t ier; + uint8_t iir; + } iir_by_prio[] =3D { + [0] =3D { ns16x50_iir_check_lsi, UART_IER_ELSI, UART_IIR_LSI }, + [1] =3D { ns16x50_iir_check_rda, UART_IER_ERDAI, UART_IIR_RDA }, + [2] =3D { ns16x50_iir_check_thr, UART_IER_ETHREI, UART_IIR_THR }, + [3] =3D { ns16x50_iir_check_msi, UART_IER_EMSI, UART_IIR_MSI }, + }; + const uint8_t *regs =3D vdev->regs; + uint8_t iir =3D 0; + unsigned int i; + + /* + * NB: every interaction w/ ns16x50 registers (except DLAB=3D1) goes + * through that call. + */ + ASSERT(spin_is_locked(&vdev->lock)); + + for ( i =3D 0; i < ARRAY_SIZE(iir_by_prio); i++ ) + { + if ( (regs[UART_IER] & iir_by_prio[i].ier) && + iir_by_prio[i].check(vdev) ) + break; + + } + if ( i =3D=3D ARRAY_SIZE(iir_by_prio) ) + iir |=3D UART_IIR_NOINT; + else + iir |=3D iir_by_prio[i].iir; + + if ( regs[UART_FCR] & UART_FCR_ENABLE ) + iir |=3D UART_IIR_FE; + + return iir; +} + +static void ns16x50_irq_assert(const struct vuart_ns16x50 *vdev) +{ + struct domain *d =3D vdev->owner; + const struct vuart_info *info =3D vdev->info; + int vector; + + if ( has_vpic(d) ) + vector =3D hvm_isa_irq_assert(d, info->irq, vioapic_get_vector); + else if ( has_vioapic(d) ) + /* TODO */ + else + ASSERT_UNREACHABLE(); + + ns16x50_debug(vdev, "IRQ#%d vector %d assert\n", info->irq, vector); +} + +static void ns16x50_irq_deassert(const struct vuart_ns16x50 *vdev) +{ + struct domain *d =3D vdev->owner; + const struct vuart_info *info =3D vdev->info; + + if ( has_vpic(d) ) + hvm_isa_irq_deassert(d, info->irq); + else if ( has_vioapic(d) ) + /* TODO */ + else + ASSERT_UNREACHABLE(); + + ns16x50_debug(vdev, "IRQ#%d deassert\n", info->irq); +} + +/* + * Assert/deassert virtual ns16x50 interrupt line. + */ +static void ns16x50_irq_check(const struct vuart_ns16x50 *vdev) +{ + uint8_t iir =3D ns16x50_iir_get(vdev); + const struct vuart_info *info =3D vdev->info; + + if ( iir & UART_IIR_NOINT ) + ns16x50_irq_deassert(vdev); + else + ns16x50_irq_assert(vdev); + + ns16x50_debug(vdev, "IRQ#%d IIR 0x%02x %s\n", info->irq, iir, + (iir & UART_IIR_NOINT) ? "deassert" : "assert"); +} + /* * Emulate 8-bit write access to ns16x50 register. */ @@ -106,6 +224,10 @@ static int ns16x50_io_write8( { switch ( reg ) { + case UART_IER: + regs[UART_IER] =3D val & UART_IER_MASK; + break; + /* NB: Firmware (e.g. OVMF) may rely on SCR presence. */ case UART_SCR: regs[UART_SCR] =3D val; @@ -115,6 +237,8 @@ static int ns16x50_io_write8( rc =3D -EINVAL; break; } + + ns16x50_irq_check(vdev); } =20 return rc; @@ -182,6 +306,14 @@ static int ns16x50_io_read8( { switch ( reg ) { + case UART_IER: + val =3D regs[UART_IER]; + break; + + case UART_IIR: /* RO */ + val =3D ns16x50_iir_get(vdev); + break; + case UART_SCR: val =3D regs[UART_SCR]; break; @@ -190,6 +322,8 @@ static int ns16x50_io_read8( rc =3D -EINVAL; break; } + + ns16x50_irq_check(vdev); } =20 *data =3D val; @@ -342,6 +476,10 @@ static int ns16x50_init(void *arg) =20 register_portio_handler(d, info->base_addr, info->size, ns16x50_io_han= dle); =20 + spin_lock(&vdev->lock); + ns16x50_irq_check(vdev); + spin_unlock(&vdev->lock); + return 0; } =20 --=20 2.51.0