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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=bTTMrmciHM4aiFMZR2LK71art6dDZteKsZ9m8QnTfYE=; b=nqZ01GmIAKqRzGL32I9Jx+XgGyZLkgmxmWoSzCh6rrmGzU1FiIQ5dagNJuuM1AFEcz JKRMuPpeiFHLnYgEsI+gYykh1G6E75NtI6X6Wxe1XZitHJqlkaszGqrHcswqsNojPNZy QMldyx2CSSbb91agwMm8wESGAl99z0cqym5n/bdIBXY/7N1oP/ILCrRkVurB7HVYnNMh lWh04fpy2cP4Ja8qxLXKMIMm2X/ckg7xNwgsoInMhcpJmP0CokXxJWJNbpRLqQl/Tl5L ZKhlX+vzbJ6EnDMKy1NQLDb84Eg/JGkyzsl3cD2PpI0wIsZEOrcH4klmO0zgVd5dqyIk QDUQ== X-Gm-Message-State: APjAAAXJGtG3mAHFVSasLfb9tSMK2iv5QV5VSK3iG/08NDYE1gogrbUd ixRtchVtnplfXOHUOzUevQSlE0KxY65PFCs7FAGWzg== X-Google-Smtp-Source: APXvYqxl6FUWzhNJmV/twRIMg5J5dk1jL54DHL5eRqSLGaUjuAJZJFHphqKMrxpAOmdnSQ0pZAWlWkDR4Yx7NICACVk= X-Received: by 2002:a1c:9695:: with SMTP id y143mr1119738wmd.103.1571720874948; Mon, 21 Oct 2019 22:07:54 -0700 (PDT) MIME-Version: 1.0 References: <20191016160649.24622-1-anup.patel@wdc.com> <20191016160649.24622-21-anup.patel@wdc.com> <1d2e9514-235e-183e-b4fc-d3becc9ce471@redhat.com> In-Reply-To: <1d2e9514-235e-183e-b4fc-d3becc9ce471@redhat.com> From: Anup Patel Date: Tue, 22 Oct 2019 10:37:43 +0530 Message-ID: Subject: Re: [PATCH v9 20/22] RISC-V: KVM: Fix race-condition in kvm_riscv_vcpu_sync_interrupts() To: Paolo Bonzini X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191021_220757_318417_5A0E0FEE X-CRM114-Status: GOOD ( 10.19 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Damien Le Moal , Palmer Dabbelt , Daniel Lezcano , "kvm@vger.kernel.org" , Radim K , Anup Patel , "linux-kernel@vger.kernel.org" , Christoph Hellwig , Atish Patra , Alexander Graf , Paul Walmsley , Alistair Francis , Thomas Gleixner , "linux-riscv@lists.infradead.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org On Mon, Oct 21, 2019 at 10:57 PM Paolo Bonzini wrote: > > On 16/10/19 18:12, Anup Patel wrote: > > + /* Read current VSIP and VSIE CSRs */ > > + vsip = csr_read(CSR_VSIP); > > + csr->vsie = csr_read(CSR_VSIE); > > + > > + /* Sync-up VSIP.SSIP bit changes does by Guest */ > > + if ((csr->vsip ^ vsip) & (1UL << IRQ_S_SOFT)) { > > + if (!test_and_set_bit(IRQ_S_SOFT, &v->irqs_pending_mask)) { > > + if (vsip & (1UL << IRQ_S_SOFT)) > > + set_bit(IRQ_S_SOFT, &v->irqs_pending); > > + else > > + clear_bit(IRQ_S_SOFT, &v->irqs_pending); > > + } > > Looks good, but I wonder if this could just be "csr->vsip = > csr_read(CSR_VSIP)", which will be fixed up by flush_interrupts on the > next entry. It's not just "csr->vsip = csr_read(CSR_VSIP" because "irqs_pending" bitmap has to be in-sync with Guest updates to VSIP because WFI trap-n-emulate will check for pending interrupts which in-turn checks "irqs_pending" bitmap. Regards, Anup _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv