From patchwork Wed Oct 9 18:59:49 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 13829090 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CC44B1E1A29; Wed, 9 Oct 2024 19:00:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728500443; cv=none; b=WVFhOaQHBsrTULAQ0XhvOSaWydIpBxbHj3Asl62LjEYXJ2qw2Uj/A/xAxfpFY/xca3g6PgHBAzQjl87W3Cqo4c29iYJ+e0aB8ICFxKD5D2cSOGaSV+QnVNRkX8Jc1LTxm7Lm/ts+Jr1p7vb6fCjcD62EUEM94n8ugPjo4PRzw0c= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728500443; c=relaxed/simple; bh=OpE1g1dXxLnO5r+wMmDCsiL9pglyj4L3QL+7VK1XQcA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=P5vK0COKCgZPTb97qwwKm9TfR9Qp6exUKLeF37awqWz8Ue5NmdUq6p89lZHsnTMu2uEwSsewt1jUISGSItg/vuARTkM6YISO4DWgs3vEQxCbG7Q0kCUrUj/M4TYby+7BRhFJvSMn11pDtfya3PxI5M09NKyBp650JfJ/sZwRfFM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TI2Djvuy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="TI2Djvuy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A7E42C4CECC; Wed, 9 Oct 2024 19:00:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1728500443; bh=OpE1g1dXxLnO5r+wMmDCsiL9pglyj4L3QL+7VK1XQcA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TI2DjvuyxL++VMijuizoWJO0ikf+NEzDOj8r6dO/mgwI8iCaL1WATmUyWDM9MDJDp 29UWwnE7kGeMNbJMHZ+GgMFPy5zHSpfbAwDQ+fOjmj5cuySPQ5TdDDf8u4woBqooZW YCCawanJNjH4bybcy+tdWbdCiaPlOxN2k5RA3+ZX9pO2pjZKeJ1qAzybekadCfIuOk KLDH+7cSZB/9/6g/LusANySEzfBjN0d4PClChLReqo6/R8bfx7JQQDFnL6skKIdPxw E2G5PpR7A6y3CgihQzegCsY+RIOocfvr8dl62f8EXVFK1HkWauY6WbluB6gFU8fyaC vqpXsBBS4wiPQ== 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 1sybvN-001wcY-Pq; Wed, 09 Oct 2024 20:00:41 +0100 From: Marc Zyngier To: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org Cc: Joey Gouly , Suzuki K Poulose , Oliver Upton , Zenghui Yu , Alexandru Elisei , Mark Brown Subject: [PATCH v4 06/36] KVM: arm64: nv: Handle CNTHCTL_EL2 specially Date: Wed, 9 Oct 2024 19:59:49 +0100 Message-Id: <20241009190019.3222687-7-maz@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20241009190019.3222687-1-maz@kernel.org> References: <20241009190019.3222687-1-maz@kernel.org> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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, joey.gouly@arm.com, suzuki.poulose@arm.com, oliver.upton@linux.dev, yuzenghui@huawei.com, alexandru.elisei@arm.com, broonie@kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false 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 3cd54656a8e2f..932d2fb7a52a0 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -157,6 +157,21 @@ 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. @@ -207,6 +222,19 @@ 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 c819c5d16613b..fd650a8789b91 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));