From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CE666606A320 for ; Mon, 19 Oct 2026 17:16:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=3KzXmtOH; dkim=fail reason="signature verification failed" (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=A1oEpCFf DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=sd6G92he5rAcV97VmGjXJ+12AyuUrDCTN7frBzyJxGw=; b=3KzXmtOHIB+/Ba L5uFe2wDqRr92PjIXQUbefl/5lMzz4nKjEE4QvvW0ljsGE9DFDHes4OVUs/cw7E1SiavEcscCNmq+ bhKZ84qVI9babg5xlChayle5EyU8ynQTYm8/NZ5Tt0qrcRVlZxjvIdj5tRvOe/yf+cSinosNaVdyz nltDGZv84uYDAB3xkSnlSxqKP7M6CqJyZHDHdCR7FABIOtfwFbGl8C5s3Syi7/RpgjBO4GoPhzDjx vAHirAyx9vXKsPITO38lrpQkihMVJIHLZbZwu9RYUZjtIqSJVRijUk9PbgNexhxBbjdKkfuTZgHOR pE7DSltdVmNVBvrve6ag==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xIqyD-000000084J1-2n8Q; Mon, 19 Oct 2026 17:16:21 +0000 Received: from out-215.mta0.migadu.com ([2001:41d0:1004:224b::d7] helo=mta0.migadu.com) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xIqyA-000000084Hz-1suQ for linux-riscv@lists.infradead.org; Mon, 19 Oct 2026 17:16:20 +0000 X-Envelope-To: linux-riscv@lists.infradead.org DKIM-Signature: a=rsa-sha256; bh=Ht0YeVNr87GBjD/XD3J4ka9N9ZFBQ94E02FEAUKrXMQ=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1792430171; v=1; x=1793034971; b=A1oEpCFfgn7hY8SlFJYdcXt93AMGLNPWFV8GWG+ZlKxM7ik9DPXqhPKqZVZcHyy62OPoWRJS 3Bzu7/+WNZSXmcOG1e0/5m+jZ6/1/FbsFujaduXfb0RTbYmXaDsBDmoMRLMuiWJ7va3EPg8IDdx 3kbwcTeZC2SYBAaqOkRofq4k= X-Envelope-To: linux-riscv@lists.infradead.org Received: by smtp.migadu.com with ESMTPS id 6fce2d4bfa616019; Mon, 19 Oct 2026 17:16:10 +0000 X-Mizu-Trace-ID: 6fce2d4bfa616019 X-Migadu-Flow: FLOW_OUT Date: Mon, 19 Oct 2026 19:16:06 +0200 From: Andrew Jones To: kvm-riscv@lists.infradead.org Cc: anup@brainfault.org, atish.patra@linux.dev, pjw@kernel.org, palmer@dabbelt.com, kvm@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] RISC-V: KVM: Convert IMSIC vsfile_lock to a raw spinlock Message-ID: References: <20261019134709.2610129-1-andrew.jones@linux.dev> X-Archived-By: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20261019134709.2610129-1-andrew.jones@linux.dev> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261019_101618_634594_8A68E4B0 X-CRM114-Status: GOOD ( 10.73 ) X-Spam-Score: -2.1 (--) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" X-Spam-Status: No, score=-9.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_EF,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Mon, Oct 19, 2026 at 03:47:09PM +0200, Andrew Jones wrote: > kvm_riscv_vcpu_aia_imsic_put() runs from the scheduler preemption > notifier with the raw runqueue lock held, so it must not take > vsfile_lock, an rwlock_t, which sleeps on PREEMPT_RT. All vsfile_lock > critical sections are short, so a raw spinlock is fine. > > Fixes: 4cec89db80ba ("RISC-V: KVM: Move HGEI[E|P] CSR access to IMSIC virtualization") > Signed-off-by: Andrew Jones > --- > v2: > - Convert vsfile_lock to raw_spinlock_t instead of adding a separate > hgei_lock [Anup] Hi Anup, Sashiko found an ABBA deadlock with this v2[1]. Making vsfile_lock exclusive serializes kvm_riscv_vcpu_aia_imsic_put(), which runs under rq->__lock, against the SW-file inject paths, which kick the vCPU (pi_lock/rq->__lock) while holding vsfile_lock. Lockdep confirms it with an EMUL mode guest, and the host then hangs (I should have tested with EMUL before...). v1 doesn't have the problem, since its hgei_lock never has anything that wakes tasks nested under it. I tested v1 in both EMUL mode and hwaccel mode [again] with lockdep and it's good. Should we take v1 instead? [1] https://sashiko.dev/#/patchset/20261019134709.2610129-1-andrew.jones@linux.dev?part=1 Thanks, drew _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv