From patchwork Fri Oct 15 13:39:29 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Ellerman X-Patchwork-Id: 1541713 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=kSZ7fuFH; dkim-atps=neutral Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org (client-ip=2404:9400:2:0:216:3eff:fee1:b9f1; helo=lists.ozlabs.org; envelope-from=linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org; receiver=) Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2404:9400:2:0:216:3eff:fee1:b9f1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by bilbo.ozlabs.org (Postfix) with ESMTPS id 4HW6pb4GGsz9shx for ; Sat, 16 Oct 2021 00:40:23 +1100 (AEDT) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4HW6pb2F3rz3c9W for ; Sat, 16 Oct 2021 00:40:23 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=kSZ7fuFH; dkim-atps=neutral X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Received: from gandalf.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4HW6nj1Z6xz2xt1 for ; Sat, 16 Oct 2021 00:39:37 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=kSZ7fuFH; dkim-atps=neutral Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4HW6nh0B3Rz4xbZ; Sat, 16 Oct 2021 00:39:36 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1634305176; bh=aT+4RSZsIeEUk+iQDrJV/Xn4f0gDbD4FWrcoDbnT2aA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kSZ7fuFHAxMta2X5UdfEzR2fyTVtBAjrNKs5EMGNAx6xt2rgkF0n5Qtf/ETNYUMyB /pWKV5sLiJyIFVFLSBJzAzDhm2+sSeG6VOKHsd0+NWuGpUhx/+Lw0+9WXu6Qp4mFFQ IBnXo7Pl60EuFXwXQnngh4x4vcjhKURxE0IxjYI4xlEBvaR8983ftXWmONYheqbt2f k5TZbr2u/lxadhABYY+uzME1jaDSk4e/hxN/FWHp4otiIbadgVHO78ORdOT3ovavMj OUFybbsx23r/WU8SOnfT7rMqt3zl2SzYU/20WMzXa5mCupUZFx1ZLAYAGHR0D1XGEX xopuNgllwgQ9Q== From: Michael Ellerman To: Subject: [PATCH 2/2] KVM: PPC: Book3S HV: Make idle_kvm_start_guest() return 0 if it went to guest Date: Sat, 16 Oct 2021 00:39:29 +1100 Message-Id: <20211015133929.832061-2-mpe@ellerman.id.au> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20211015133929.832061-1-mpe@ellerman.id.au> References: <20211015133929.832061-1-mpe@ellerman.id.au> MIME-Version: 1.0 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm-ppc@vger.kernel.org, npiggin@gmail.com Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" We call idle_kvm_start_guest() from power7_offline() if the thread has been requested to enter KVM. We pass it the SRR1 value that was returned from power7_idle_insn() which tells us what sort of wakeup we're processing. Depending on the SRR1 value we pass in, the KVM code might enter the guest, or it might return to us to do some host action if the wakeup requires it. If idle_kvm_start_guest() is able to handle the wakeup, and enter the guest it is supposed to indicate that by returning a zero SRR1 value to us. That was the behaviour prior to commit 10d91611f426 ("powerpc/64s: Reimplement book3s idle code in C"), however in that commit the handling of SRR1 was reworked, and the zeroing behaviour was lost. Returning from idle_kvm_start_guest() without zeroing the SRR1 value can confuse the host offline code, causing the guest to crash and other weirdness. Fixes: 10d91611f426 ("powerpc/64s: Reimplement book3s idle code in C") Cc: stable@vger.kernel.org # v5.2+ Signed-off-by: Michael Ellerman --- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index ec57952b60b0..eb776d0c5d8e 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -264,6 +264,7 @@ _GLOBAL(idle_kvm_start_guest) stdu r1, -SWITCH_FRAME_SIZE(r4) // Switch to new frame on emergency stack mr r1, r4 + std r3, 32(r1) // Save SRR1 wakeup value SAVE_NVGPRS(r1) /* @@ -315,6 +316,10 @@ _GLOBAL(idle_kvm_start_guest) kvm_secondary_got_guest: + // About to go to guest, clear saved SRR1 + li r0, 0 + std r0, 32(r1) + /* Set HSTATE_DSCR(r13) to something sensible */ ld r6, PACA_DSCR_DEFAULT(r13) std r6, HSTATE_DSCR(r13) @@ -394,8 +399,8 @@ _GLOBAL(idle_kvm_start_guest) mfspr r4, SPRN_LPCR rlwimi r4, r3, 0, LPCR_PECE0 | LPCR_PECE1 mtspr SPRN_LPCR, r4 - /* set up r3 for return */ - mfspr r3,SPRN_SRR1 + // Return SRR1 wakeup value, or 0 if we went into the guest + ld r3, 32(r1) REST_NVGPRS(r1) ld r1, 0(r1) // Switch back to caller stack ld r0, 16(r1) // Reload LR