From patchwork Mon Feb 5 10:34:08 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 13545181 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 D600EC48291 for ; Mon, 5 Feb 2024 10:35:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=bCJJiSV2Mx4ZFf+RVfX5TErqMcrZS2f1yuZDwRkdZJw=; b=ogLl+m9O4wQmQ5 ETOzJHAq3SwpmpVTwoyD0UEvjTVYEegVmI4K//R5Z8AUtKm0HkESvA+jWZBIrL7oOQUPvgGvCVCzP jftSFyMDvh0Fs4D6iPyed5OTWZUI96BjJYoNQvOr8MBuke1NgYzpJyQKyyHfR65Aio0M5fF1P3EKy GGqobWLPlhAHahW8stf8H/gODemOM1wBejXjrST/4XeuL66o0eOE3MY9xR6vV34sum+P3f6miHOZS jDi7vcXTWLOWE/WQp5xUf6rRiitJvpwvT1pcrHJuE7y/usf+WcsGlwszktFUupUA3LfEVArwFrLPi vEBIafTJvogQ9x4zywuA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rWwJU-00000002pCJ-31Z9; Mon, 05 Feb 2024 10:34:56 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rWwJN-00000002p3u-2Ryd for linux-arm-kernel@lists.infradead.org; Mon, 05 Feb 2024 10:34:51 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 6739560FE2; Mon, 5 Feb 2024 10:34:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 77E7BC43330; Mon, 5 Feb 2024 10:34:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1707129287; bh=5vRlXGNPw+t8CSN/WB8SMPvqzMf0CIBVixpJqhMcQMg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=G4mtYSO/BB6tNzu7sdy3W651n3dnl5btLA+QyClzsCVU7uCUEKfuWj3dGdW/wHs9/ DksgoSt/4MzmOTa7kaYBcV5LtYPHh5wFSBJvy/Q5dH+hCBpBdb7WFmNmyMIbpPOUXZ 40MTRwQu5yFtSMIoWTf/pZJbrv/++iZVa3/7/cGX+w/iUPmwrBGgRrGCNt2bsHi+cE Vz8sa7nUYXc0T6D+EJta8r9y56ce7h37LNAgQa+8uUpFGQq9eeG9pX3SF/2MTB5YuR aaNxlUYc/ryccIcGhj4ynRwNmePmvE5LLB/WHMaEsfywz+d+6vDCJOTB5WKFFRQlJe y2eGDWHVGOUIg== 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 1rWwJJ-000Nc3-GA; Mon, 05 Feb 2024 10:34:45 +0000 From: Marc Zyngier To: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org Cc: James Morse , Suzuki K Poulose , Oliver Upton , Zenghui Yu , Catalin Marinas , Will Deacon , Joey Gouly , Mark Brown Subject: [PATCH v3 03/26] KVM: arm64: nv: Add sanitising to VNCR-backed sysregs Date: Mon, 5 Feb 2024 10:34:08 +0000 Message-Id: <20240205103431.1104133-4-maz@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240205103431.1104133-1-maz@kernel.org> References: <20240205103431.1104133-1-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, james.morse@arm.com, suzuki.poulose@arm.com, oliver.upton@linux.dev, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, joey.gouly@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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240205_023449_765886_B81D5ADB X-CRM114-Status: GOOD ( 19.49 ) 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 VNCR-backed "registers" are actually only memory. Which means that there is zero control over what the guest can write, and that it is the hypervisor's job to actually sanitise the content of the backing store. Yeah, this is fun. In order to preserve some form of sanity, add a repainting mechanism that makes use of a per-VM set of RES0/RES1 masks, one pair per VNCR register. These masks get applied on access to the backing store via __vcpu_sys_reg(), ensuring that the state that is consumed by KVM is correct. So far, nothing populates these masks, but stay tuned. Signed-off-by: Marc Zyngier Reviewed-by: Joey Gouly --- arch/arm64/include/asm/kvm_host.h | 22 ++++++++++++++++- arch/arm64/kvm/arm.c | 1 + arch/arm64/kvm/nested.c | 41 ++++++++++++++++++++++++++++++- 3 files changed, 62 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 527da3d2cedb..8cda003d6267 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -238,6 +238,8 @@ static inline u16 kvm_mpidr_index(struct kvm_mpidr_data *data, u64 mpidr) return index; } +struct kvm_sysreg_masks; + struct kvm_arch { struct kvm_s2_mmu mmu; @@ -312,6 +314,9 @@ struct kvm_arch { #define KVM_ARM_ID_REG_NUM (IDREG_IDX(sys_reg(3, 0, 0, 7, 7)) + 1) u64 id_regs[KVM_ARM_ID_REG_NUM]; + /* Masks for VNCR-baked sysregs */ + struct kvm_sysreg_masks *sysreg_masks; + /* * For an untrusted host VM, 'pkvm.handle' is used to lookup * the associated pKVM instance in the hypervisor. @@ -474,6 +479,13 @@ enum vcpu_sysreg { NR_SYS_REGS /* Nothing after this line! */ }; +struct kvm_sysreg_masks { + struct { + u64 res0; + u64 res1; + } mask[NR_SYS_REGS - __VNCR_START__]; +}; + struct kvm_cpu_context { struct user_pt_regs regs; /* sp = sp_el0 */ @@ -868,7 +880,15 @@ static inline u64 *__ctxt_sys_reg(const struct kvm_cpu_context *ctxt, int r) #define ctxt_sys_reg(c,r) (*__ctxt_sys_reg(c,r)) -#define __vcpu_sys_reg(v,r) (ctxt_sys_reg(&(v)->arch.ctxt, (r))) +u64 kvm_vcpu_sanitise_vncr_reg(const struct kvm_vcpu *, enum vcpu_sysreg); +#define __vcpu_sys_reg(v,r) \ + (*({ \ + const struct kvm_cpu_context *ctxt = &(v)->arch.ctxt; \ + u64 *__r = __ctxt_sys_reg(ctxt, (r)); \ + if (vcpu_has_nv((v)) && (r) >= __VNCR_START__) \ + *__r = kvm_vcpu_sanitise_vncr_reg((v), (r)); \ + __r; \ + })) u64 vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, int reg); void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg); diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index a25265aca432..c063e84fc72c 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -206,6 +206,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm) pkvm_destroy_hyp_vm(kvm); kfree(kvm->arch.mpidr_data); + kfree(kvm->arch.sysreg_masks); kvm_destroy_vcpus(kvm); kvm_unshare_hyp(kvm, kvm + 1); diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index d55e809e26cb..c976cd4b8379 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -163,15 +163,54 @@ static u64 limit_nv_id_reg(u32 id, u64 val) return val; } + +u64 kvm_vcpu_sanitise_vncr_reg(const struct kvm_vcpu *vcpu, enum vcpu_sysreg sr) +{ + u64 v = ctxt_sys_reg(&vcpu->arch.ctxt, sr); + struct kvm_sysreg_masks *masks; + + masks = vcpu->kvm->arch.sysreg_masks; + + if (masks) { + sr -= __VNCR_START__; + + v &= ~masks->mask[sr].res0; + v |= masks->mask[sr].res1; + } + + return v; +} + +static void __maybe_unused set_sysreg_masks(struct kvm *kvm, int sr, u64 res0, u64 res1) +{ + int i = sr - __VNCR_START__; + + kvm->arch.sysreg_masks->mask[i].res0 = res0; + kvm->arch.sysreg_masks->mask[i].res1 = res1; +} + int kvm_init_nv_sysregs(struct kvm *kvm) { + int ret = 0; + mutex_lock(&kvm->arch.config_lock); + if (kvm->arch.sysreg_masks) + goto out; + + kvm->arch.sysreg_masks = kzalloc(sizeof(*(kvm->arch.sysreg_masks)), + GFP_KERNEL); + if (!kvm->arch.sysreg_masks) { + ret = -ENOMEM; + goto out; + } + for (int i = 0; i < KVM_ARM_ID_REG_NUM; i++) kvm->arch.id_regs[i] = limit_nv_id_reg(IDX_IDREG(i), kvm->arch.id_regs[i]); +out: mutex_unlock(&kvm->arch.config_lock); - return 0; + return ret; }