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: 13762154 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 8C8811D68F; Tue, 13 Aug 2024 14:47:57 +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=1723560477; cv=none; b=svlva5izgerxkztL/NXQTMcLao1DjKOsBwVCOAK1RkzfF4V9vE6PeJ50UzGZNDBpFSvonZoh0BBYyT3F/tdO4fkzD08GQd9OZhRh6KX3CYFf2Sxpmq+R88IG8WmnlJrS23Vs/vhkM75RYH73OE+3+jH8M4oqb9z96Bph0JWa+98= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723560477; c=relaxed/simple; bh=tQhs6sQmLRKSXnFl/3yZscrAIYRb7Tz89+/QXGEXSMs=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=d2jKcF7ccjFYmK3FBmXDzPet/fdqSMgZ54PG+1kbVlY/upRZDqm1fOJ6ygrWsIgut2s7BVy9lzzxH2dxfwcJXkQa3G9BI1nySC/MIg3DkykqzDm2kd4D8MW76emxRkAW+yX9p3XYt0Mh0SjQbd9wXN430xT2B3eBeBb0CDlflk4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mua16IWe; 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="mua16IWe" 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> 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, 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 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));