From patchwork Mon Oct 26 09:51:16 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 11856271 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C4E4FC4363A for ; Mon, 26 Oct 2020 10:09:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 72397223EA for ; Mon, 26 Oct 2020 10:09:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603706962; bh=SurefXaVHTkq8zMCu3OywCnUsZc0fFu5URrqoO8B4xE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=0PgBR8+d5U7CDasN+JTqH5SJe7jv+3nE67X+AZnXn72RjymKkuBxXqkVWjjIspFgP OEIs7zoKIBKPziDkjK97j5tLDdbdHne7McGQGHGt8dCrW+k1ynb67QTI28DyM8As03 87u8X97s1nGSg0PSK98aJf/Vv2mqTzSyVoIj5JJ0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1768394AbgJZJvq (ORCPT ); Mon, 26 Oct 2020 05:51:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:44336 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1744149AbgJZJvg (ORCPT ); Mon, 26 Oct 2020 05:51:36 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 52CEB222EC; Mon, 26 Oct 2020 09:51:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603705895; bh=SurefXaVHTkq8zMCu3OywCnUsZc0fFu5URrqoO8B4xE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=i/7ZdOxQbzEv8h+8z1RnD1VA6PKO8a90na1JhFWRRUwezTCrkJQpKzyhY4ABHGETj 6Q6518zDC22x6MwQ5nXo+iogozTR7Xnx4mMD80QydAXT7rwuOcWgajDgM5VGZkTFhf QzL7Q1dNz6BLfO9sKxCrXefFp7f3KqO0nheKeAaI= Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1kWzA5-004HZn-F6; Mon, 26 Oct 2020 09:51:33 +0000 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org Cc: James Morse , Julien Thierry , Suzuki K Poulose , Andrew Scull , Will Deacon , Quentin Perret , kernel-team@android.com Subject: [PATCH 8/8] KVM: arm64: Avoid repetitive stack access on host EL1 to EL2 exception Date: Mon, 26 Oct 2020 09:51:16 +0000 Message-Id: <20201026095116.72051-9-maz@kernel.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201026095116.72051-1-maz@kernel.org> References: <20201026095116.72051-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, ascull@google.com, will@kernel.org, qperret@google.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Registers x0/x1 get repeateadly pushed and poped during a host HVC call. Instead, leave the registers on the stack, saving a store instruction on the fast path for an add on the slow path. Signed-off-by: Marc Zyngier Reviewed-by: Alexandru Elisei --- arch/arm64/kvm/hyp/nvhe/host.S | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S index e2d316d13180..7b69f9ff8da0 100644 --- a/arch/arm64/kvm/hyp/nvhe/host.S +++ b/arch/arm64/kvm/hyp/nvhe/host.S @@ -13,8 +13,6 @@ .text SYM_FUNC_START(__host_exit) - stp x0, x1, [sp, #-16]! - get_host_ctxt x0, x1 /* Store the host regs x2 and x3 */ @@ -99,13 +97,14 @@ SYM_FUNC_END(__hyp_do_panic) mrs x0, esr_el2 lsr x0, x0, #ESR_ELx_EC_SHIFT cmp x0, #ESR_ELx_EC_HVC64 - ldp x0, x1, [sp], #16 + ldp x0, x1, [sp] // Don't fixup the stack yet b.ne __host_exit /* Check for a stub HVC call */ cmp x0, #HVC_STUB_HCALL_NR b.hs __host_exit + add sp, sp, #16 /* * Compute the idmap address of __kvm_handle_stub_hvc and * jump there. Since we use kimage_voffset, do not use the