From patchwork Tue Aug 13 14:47:29 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 13762171 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id E4B98C52D7C for ; Tue, 13 Aug 2024 14:50:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=8XtGUDS/3sRlHGtFzkVLYOr8L5hLLoXU+1oyJCSz78Q=; b=lzBZOLmD/G5D4f+ltVZI7s1oOa KVOkZIysDjsQbvD2VTKhcPd70llbw7ggpx20wrc240N1HQ1zQ3lemPm1b2D2neZa8bgRSfYrc12ir k7PMLhmrNoAszyg7BdX8i2/z8yqfQHSsw5sdw5KfXT0lG65iCrGmzcu9fW6Q7cOlDKfhm8x0usQcv /jCh4ToexFinZYLpvv/OKS39rqS8y5Lhwhwz082ecUK7CK6x/LobYJl9jlTEEPuN7DBjqgvlttj7A PErMtpMzbTq+OPNkFQEa5wZHG6pcgqsBipogqbifIv+lnL94Z8cLEffryybECDiuQcaLFzERm3/6C Mlmo132Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sdsqL-0000000455j-1Rpb; Tue, 13 Aug 2024 14:49:49 +0000 Received: from sin.source.kernel.org ([2604:1380:40e1:4800::1]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sdsoa-000000044bY-1Dik for linux-arm-kernel@lists.infradead.org; Tue, 13 Aug 2024 14:48:02 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id 37F03CE13A9; Tue, 13 Aug 2024 14:47:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 39227C4AF0F; Tue, 13 Aug 2024 14:47:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1723560477; bh=tQhs6sQmLRKSXnFl/3yZscrAIYRb7Tz89+/QXGEXSMs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mua16IWe6C4QYn718rOjMLNbcblOr9rsWmY/KNFHaN/rzsgwnJ2FYozg3S0ZXHdn3 XQqvSKUmzsFM35dhx/cX4M+iQX6oPUYRLzg5SEHAiotV6yp8PnENggPN7wRFON2QZq WT1vZ/oVaslkagtXHsZPDncrFnM69Log5qb2FwBXSKKldd+FZdgwQJbXZLMhAB3+Sm GjBnQF7BchOLmTtemcYGleEXt49v8BPK0ce0BtIDO1bA2ftTGiNFaXhypcghIv/kVH GsvtmU3jrhUoJvlpf2ds+ZBh1YkfHP4iiy4SrPisFAecIV+fdL6J8wfYDGLGtsdqQv /xUCotHq+So0g== Received: from sofa.misterjones.org ([185.219.108.64] helo=valley-girl.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1sdsoV-003O27-D7; Tue, 13 Aug 2024 15:47:55 +0100 From: Marc Zyngier To: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org Cc: James Morse , Suzuki K Poulose , Oliver Upton , Zenghui Yu , Joey Gouly , Alexandru Elisei Subject: [PATCH 01/10] KVM: arm64: nv: Handle CNTHCTL_EL2 specially Date: Tue, 13 Aug 2024 15:47:29 +0100 Message-Id: <20240813144738.2048302-2-maz@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240813144738.2048302-1-maz@kernel.org> References: <20240813144738.2048302-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, james.morse@arm.com, suzuki.poulose@arm.com, oliver.upton@linux.dev, yuzenghui@huawei.com, joey.gouly@arm.com, alexandru.elisei@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-20240813_074800_789192_2AF5022A X-CRM114-Status: GOOD ( 14.48 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Accessing CNTHCTL_EL2 is fraught with danger if running with HCR_EL2.E2H=1: half of the bits are held in CNTKCTL_EL1, and thus can be changed behind our back, while the rest lives in the CNTHCTL_EL2 shadow copy that is memory-based. Yes, this is a lot of fun! Make sure that we merge the two on read access, while we can write to CNTKCTL_EL1 in a more straightforward manner. Signed-off-by: Marc Zyngier --- arch/arm64/kvm/sys_regs.c | 28 ++++++++++++++++++++++++++++ include/kvm/arm_arch_timer.h | 3 +++ 2 files changed, 31 insertions(+) diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index c90324060436..95832881fd66 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -140,6 +140,21 @@ u64 vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, int reg) if (!is_hyp_ctxt(vcpu)) goto memory_read; + /* + * CNTHCTL_EL2 requires some special treatment to + * account for the bits that can be set via CNTKCTL_EL1. + */ + switch (reg) { + case CNTHCTL_EL2: + if (vcpu_el2_e2h_is_set(vcpu)) { + val = read_sysreg_el1(SYS_CNTKCTL); + val &= CNTKCTL_VALID_BITS; + val |= __vcpu_sys_reg(vcpu, reg) & ~CNTKCTL_VALID_BITS; + return val; + } + break; + } + /* * If this register does not have an EL1 counterpart, * then read the stored EL2 version. @@ -190,6 +205,19 @@ void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg) */ __vcpu_sys_reg(vcpu, reg) = val; + switch (reg) { + case CNTHCTL_EL2: + /* + * If E2H=0, CNHTCTL_EL2 is a pure shadow register. + * Otherwise, some of the bits are backed by + * CNTKCTL_EL1, while the rest is kept in memory. + * Yes, this is fun stuff. + */ + if (vcpu_el2_e2h_is_set(vcpu)) + write_sysreg_el1(val, SYS_CNTKCTL); + return; + } + /* No EL1 counterpart? We're done here.? */ if (reg == el1r) return; diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h index c819c5d16613..fd650a8789b9 100644 --- a/include/kvm/arm_arch_timer.h +++ b/include/kvm/arm_arch_timer.h @@ -147,6 +147,9 @@ u64 timer_get_cval(struct arch_timer_context *ctxt); void kvm_timer_cpu_up(void); void kvm_timer_cpu_down(void); +/* CNTKCTL_EL1 valid bits as of DDI0487J.a */ +#define CNTKCTL_VALID_BITS (BIT(17) | GENMASK_ULL(9, 0)) + static inline bool has_cntpoff(void) { return (has_vhe() && cpus_have_final_cap(ARM64_HAS_ECV_CNTPOFF));