From mboxrd@z Thu Jan 1 00:00:00 1970 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=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS 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 61AD6C433DF for ; Thu, 28 May 2020 12:38:58 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2721D20707 for ; Thu, 28 May 2020 12:38:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="W+XWfHE5"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="Z3rJ1R+b" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2721D20707 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:Message-ID:References:In-Reply-To:Subject:To:From: Date:MIME-Version:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=si7Xq2YhcdRztcThC88CYmwUHZkSc/KDF4ueFhVXMmQ=; b=W+XWfHE5xTp+fGAdxX8ixWtOZ NYx09pZRUppt5WvPQ/s/YiTZ6XN3rCrn3asA0hh82IVj5wHGBXqQ1zdsvUOqdKNZP/7Z+dNnAN2+D gbXhi11rOUD+Apqr9eH9P/CwC5zYVhSo+QBOFC44WpHBWMNs+WbiJn57kDuqNEhXQceTvcJT+CppA OqNNYUt6IRG8BwaawByjaDjgYkq6yrCb0TioKhZwkgPT+4y30vmZ0zMLL8K9sOKUV9yrMNNQ9BfD0 T7UBCc2OCHm8fkExgdJYUoiNzn4Q+fAZLjj56cuA/S7hV223Vf+IWyM0N9fuZxiN/wRIOFfYzPAbD 9y7SKy/EA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jeHoG-00010S-7o; Thu, 28 May 2020 12:38:56 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jeHoD-0000z8-9r for linux-arm-kernel@lists.infradead.org; Thu, 28 May 2020 12:38:54 +0000 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 D4FA6206F1; Thu, 28 May 2020 12:38:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590669533; bh=BZ3w3GKugfaLInyp5RM4AxYALpTVIM2qk6X84rH4MZ0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Z3rJ1R+bzPOdlblNYhPa8gmGr4lF28LeXZT53IK4yg4k6erfxGYql74WkmlXVUann bQaelJYw+9Evjwn1vQuA2fIBs9erGxfL+xVjdMxGbWtvcfojUY4uZlibadAf6vU7Yc XFVkRPpsxlDCWwmOWnMjC8YSn4ZczW5sSqK7Caac= Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1jeHoB-00FzCQ-BM; Thu, 28 May 2020 13:38:51 +0100 MIME-Version: 1.0 Date: Thu, 28 May 2020 13:38:51 +0100 From: Marc Zyngier To: James Morse Subject: Re: [PATCH 2/3] KVM: arm64: Stop save/restoring ACTLR_EL1 In-Reply-To: <4d42a5db0b573c7a184aea654829a06c@kernel.org> References: <20200526161834.29165-1-james.morse@arm.com> <20200526161834.29165-3-james.morse@arm.com> <4d42a5db0b573c7a184aea654829a06c@kernel.org> User-Agent: Roundcube Webmail/1.4.4 Message-ID: <07d09551c456c6be326473e003def3ab@kernel.org> X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: james.morse@arm.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200528_053853_408449_815F261C X-CRM114-Status: GOOD ( 14.25 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Julien Thierry , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, Suzuki K Poulose Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2020-05-28 13:36, Marc Zyngier wrote: > On 2020-05-26 17:18, James Morse wrote: >> KVM sets HCR_EL2.TACR (which it calls HCR_TAC) via HCR_GUEST_FLAGS. > > TAC is a leftover from 32bit. > >> This means ACTLR* accesses from the guest are always trapped, and >> always return the value in the sys_regs array. >> >> The guest can't change the value of these registers, so we are >> save restoring the reset value, which came from the host. >> >> Stop save/restoring this register. >> >> This also stops this register being affected by sysregs_loaded_on_cpu, >> so we can provide 32 bit accessors that always use the in-memory copy. >> >> Signed-off-by: James Morse >> --- >> arch/arm64/kvm/hyp/sysreg-sr.c | 2 -- >> arch/arm64/kvm/sys_regs.c | 2 -- >> 2 files changed, 4 deletions(-) >> >> diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c >> b/arch/arm64/kvm/hyp/sysreg-sr.c >> index 75b1925763f1..57116cf3a1a5 100644 >> --- a/arch/arm64/kvm/hyp/sysreg-sr.c >> +++ b/arch/arm64/kvm/hyp/sysreg-sr.c >> @@ -44,7 +44,6 @@ static void __hyp_text >> __sysreg_save_el1_state(struct kvm_cpu_context *ctxt) >> { >> ctxt->sys_regs[CSSELR_EL1] = read_sysreg(csselr_el1); >> ctxt->sys_regs[SCTLR_EL1] = read_sysreg_el1(SYS_SCTLR); >> - ctxt->sys_regs[ACTLR_EL1] = read_sysreg(actlr_el1); >> ctxt->sys_regs[CPACR_EL1] = read_sysreg_el1(SYS_CPACR); >> ctxt->sys_regs[TTBR0_EL1] = read_sysreg_el1(SYS_TTBR0); >> ctxt->sys_regs[TTBR1_EL1] = read_sysreg_el1(SYS_TTBR1); >> @@ -133,7 +132,6 @@ static void __hyp_text >> __sysreg_restore_el1_state(struct kvm_cpu_context *ctxt) >> isb(); >> } >> >> - write_sysreg(ctxt->sys_regs[ACTLR_EL1], actlr_el1); > > If we don't need to save/restore it, we can also drop its presence > in the sys_regs array. > >> write_sysreg_el1(ctxt->sys_regs[CPACR_EL1], SYS_CPACR); >> write_sysreg_el1(ctxt->sys_regs[TTBR0_EL1], SYS_TTBR0); >> write_sysreg_el1(ctxt->sys_regs[TTBR1_EL1], SYS_TTBR1); >> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c >> index 2eda539f3281..aae58513025c 100644 >> --- a/arch/arm64/kvm/sys_regs.c >> +++ b/arch/arm64/kvm/sys_regs.c >> @@ -81,7 +81,6 @@ u64 vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, >> int reg) >> switch (reg) { >> case CSSELR_EL1: return read_sysreg_s(SYS_CSSELR_EL1); >> case SCTLR_EL1: return read_sysreg_s(SYS_SCTLR_EL12); >> - case ACTLR_EL1: return read_sysreg_s(SYS_ACTLR_EL1); >> case CPACR_EL1: return read_sysreg_s(SYS_CPACR_EL12); >> case TTBR0_EL1: return read_sysreg_s(SYS_TTBR0_EL12); >> case TTBR1_EL1: return read_sysreg_s(SYS_TTBR1_EL12); >> @@ -124,7 +123,6 @@ void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 >> val, int reg) >> switch (reg) { >> case CSSELR_EL1: write_sysreg_s(val, SYS_CSSELR_EL1); return; >> case SCTLR_EL1: write_sysreg_s(val, SYS_SCTLR_EL12); return; >> - case ACTLR_EL1: write_sysreg_s(val, SYS_ACTLR_EL1); return; >> case CPACR_EL1: write_sysreg_s(val, SYS_CPACR_EL12); return; >> case TTBR0_EL1: write_sysreg_s(val, SYS_TTBR0_EL12); return; >> case TTBR1_EL1: write_sysreg_s(val, SYS_TTBR1_EL12); return; > > It strikes me that we don't even have a trap handler for this sysreg, > whether it is 32 or 64bit... That's a bit unfortunate, to say the > least... Ah, no. the sucker is hidden away in "generic_v8"... M. -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel