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 Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6594EC433EF for ; Wed, 2 Feb 2022 12:10:00 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id DB5764B0BD; Wed, 2 Feb 2022 07:09:59 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id qG8k6s1KGKal; Wed, 2 Feb 2022 07:09:57 -0500 (EST) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id CAC8F4B0BE; Wed, 2 Feb 2022 07:09:57 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 9943E4B0B9 for ; Wed, 2 Feb 2022 07:09:56 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id lz4TEX4aJQjQ for ; Wed, 2 Feb 2022 07:09:54 -0500 (EST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 441A24B0B6 for ; Wed, 2 Feb 2022 07:09:54 -0500 (EST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 751E71FB; Wed, 2 Feb 2022 04:09:53 -0800 (PST) Received: from monolith.localdoman (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A66663F718; Wed, 2 Feb 2022 04:09:50 -0800 (PST) Date: Wed, 2 Feb 2022 12:10:00 +0000 From: Alexandru Elisei To: Marc Zyngier Subject: Re: [PATCH v6 06/64] KVM: arm64: nv: Add nested virt VCPU primitives for vEL2 VCPU state Message-ID: References: <20220128121912.509006-1-maz@kernel.org> <20220128121912.509006-7-maz@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220128121912.509006-7-maz@kernel.org> Cc: kernel-team@android.com, kvm@vger.kernel.org, Andre Przywara , Christoffer Dall , Chase Conklin , kvmarm@lists.cs.columbia.edu, mihai.carabas@oracle.com, Ganapatrao Kulkarni , "Russell King \(Oracle\)" , linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Hi Marc, On Fri, Jan 28, 2022 at 12:18:14PM +0000, Marc Zyngier wrote: > From: Christoffer Dall > > When running a nested hypervisor we commonly have to figure out if > the VCPU mode is running in the context of a guest hypervisor or guest > guest, or just a normal guest. > > Add convenient primitives for this. > > Reviewed-by: Russell King (Oracle) > Signed-off-by: Christoffer Dall > Signed-off-by: Marc Zyngier > --- > arch/arm64/include/asm/kvm_emulate.h | 53 ++++++++++++++++++++++++++++ > 1 file changed, 53 insertions(+) > > diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h > index d62405ce3e6d..ea9a130c4b6a 100644 > --- a/arch/arm64/include/asm/kvm_emulate.h > +++ b/arch/arm64/include/asm/kvm_emulate.h > @@ -178,6 +178,59 @@ static __always_inline void vcpu_set_reg(struct kvm_vcpu *vcpu, u8 reg_num, > vcpu_gp_regs(vcpu)->regs[reg_num] = val; > } > > +static inline bool vcpu_is_el2_ctxt(const struct kvm_cpu_context *ctxt) > +{ > + switch (ctxt->regs.pstate & (PSR_MODE32_BIT | PSR_MODE_MASK)) { > + case PSR_MODE_EL2h: > + case PSR_MODE_EL2t: > + return true; > + default: > + return false; > + } > +} > + > +static inline bool vcpu_is_el2(const struct kvm_vcpu *vcpu) > +{ > + return vcpu_is_el2_ctxt(&vcpu->arch.ctxt); > +} > + > +static inline bool __vcpu_el2_e2h_is_set(const struct kvm_cpu_context *ctxt) > +{ > + return ctxt_sys_reg(ctxt, HCR_EL2) & HCR_E2H; > +} > + > +static inline bool vcpu_el2_e2h_is_set(const struct kvm_vcpu *vcpu) > +{ > + return __vcpu_el2_e2h_is_set(&vcpu->arch.ctxt); > +} > + > +static inline bool __vcpu_el2_tge_is_set(const struct kvm_cpu_context *ctxt) > +{ > + return ctxt_sys_reg(ctxt, HCR_EL2) & HCR_TGE; > +} > + > +static inline bool vcpu_el2_tge_is_set(const struct kvm_vcpu *vcpu) > +{ > + return __vcpu_el2_tge_is_set(&vcpu->arch.ctxt); > +} > + > +static inline bool __is_hyp_ctxt(const struct kvm_cpu_context *ctxt) > +{ > + /* > + * We are in a hypervisor context if the vcpu mode is EL2 or > + * E2H and TGE bits are set. The latter means we are in the user space > + * of the VHE kernel. ARMv8.1 ARM describes this as 'InHost' > + */ > + return vcpu_is_el2_ctxt(ctxt) || > + (__vcpu_el2_e2h_is_set(ctxt) && __vcpu_el2_tge_is_set(ctxt)) || > + WARN_ON(__vcpu_el2_tge_is_set(ctxt)); Why the WARN_ON? Wouldn't it be easy for a guest to flood the host's dmesg with warnings by setting HCR_EL2.{E2H,TGE} = {0, 1} and then repeatedly accessing EL2 registers (for example)? > +} > + > +static inline bool is_hyp_ctxt(const struct kvm_vcpu *vcpu) When KVM boots at EL2 and FEAT_VHE is not implemented it prints to dmesg: [ 1.352302] kvm [1]: Hyp mode initialized successfully I take it in that context "Hyp" means "EL2 NVHE", because when E2H,TGE are set the message changes to: [ 0.037683] kvm [1]: VHE mode initialized successfully In this file, in the function is_kernel_in_hyp_mode(), "hyp" actually means that the exception level is EL2. In kvm/arm.c, "hyp" also means EL2 (or maybe EL2 NVHE?). Wouldn't it be nice to avoid having "hyp" mean yet another thing and replace it with "hypervisor" in these two functions? Thanks, Alex > +{ > + return __is_hyp_ctxt(&vcpu->arch.ctxt); > +} > + > /* > * The layout of SPSR for an AArch32 state is different when observed from an > * AArch64 SPSR_ELx or an AArch32 SPSR_*. This function generates the AArch32 > -- > 2.30.2 > _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm