From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 854D4DF40 for ; Mon, 15 May 2023 16:39:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DF59BC433D2; Mon, 15 May 2023 16:39:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1684168794; bh=b24/jxuW7WhvTldd3iDQErsqx6y3yEwslCuaJRJsrj4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fPIkiXiOpffvb6gR28WSBjkWFUw/ddh7M6JV1twZJjcH6SGL16mIX+IpKkGbs9GZM ZIOw4BJ62K1zIqk+q3PgB3DFwyZrxUBRkl/J0iFK+4gQAg8BicHFtYG+NZmcHKS2jP y12OV1FKxFqLvcmibuhMBx+6G6I3fro29TRl4iYg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Saurabh Sengar , Thomas Gleixner , Sasha Levin Subject: [PATCH 4.19 043/191] x86/ioapic: Dont return 0 from arch_dynirq_lower_bound() Date: Mon, 15 May 2023 18:24:40 +0200 Message-Id: <20230515161708.750921329@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230515161707.203549282@linuxfoundation.org> References: <20230515161707.203549282@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Saurabh Sengar [ Upstream commit 5af507bef93c09a94fb8f058213b489178f4cbe5 ] arch_dynirq_lower_bound() is invoked by the core interrupt code to retrieve the lowest possible Linux interrupt number for dynamically allocated interrupts like MSI. The x86 implementation uses this to exclude the IO/APIC GSI space. This works correctly as long as there is an IO/APIC registered, but returns 0 if not. This has been observed in VMs where the BIOS does not advertise an IO/APIC. 0 is an invalid interrupt number except for the legacy timer interrupt on x86. The return value is unchecked in the core code, so it ends up to allocate interrupt number 0 which is subsequently considered to be invalid by the caller, e.g. the MSI allocation code. The function has already a check for 0 in the case that an IO/APIC is registered, as ioapic_dynirq_base is 0 in case of device tree setups. Consolidate this and zero check for both ioapic_dynirq_base and gsi_top, which is used in the case that no IO/APIC is registered. Fixes: 3e5bedc2c258 ("x86/apic: Fix arch_dynirq_lower_bound() bug for DT enabled machines") Signed-off-by: Saurabh Sengar Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/1679988604-20308-1-git-send-email-ssengar@linux.microsoft.com Signed-off-by: Sasha Levin --- arch/x86/kernel/apic/io_apic.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index 677508baf95a0..af59aa9c55233 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -2449,17 +2449,21 @@ static int io_apic_get_redir_entries(int ioapic) unsigned int arch_dynirq_lower_bound(unsigned int from) { + unsigned int ret; + /* * dmar_alloc_hwirq() may be called before setup_IO_APIC(), so use * gsi_top if ioapic_dynirq_base hasn't been initialized yet. */ - if (!ioapic_initialized) - return gsi_top; + ret = ioapic_dynirq_base ? : gsi_top; + /* - * For DT enabled machines ioapic_dynirq_base is irrelevant and not - * updated. So simply return @from if ioapic_dynirq_base == 0. + * For DT enabled machines ioapic_dynirq_base is irrelevant and + * always 0. gsi_top can be 0 if there is no IO/APIC registered. + * 0 is an invalid interrupt number for dynamic allocations. Return + * @from instead. */ - return ioapic_dynirq_base ? : from; + return ret ? : from; } #ifdef CONFIG_X86_32 -- 2.39.2