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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hiiAW-0000fc-9E; Wed, 03 Jul 2019 16:31:40 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hiiAS-0000e5-64 for linux-arm-kernel@lists.infradead.org; Wed, 03 Jul 2019 16:31:38 +0000 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 90D22344; Wed, 3 Jul 2019 09:31:35 -0700 (PDT) Received: from [10.1.197.61] (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 196CB3F718; Wed, 3 Jul 2019 09:31:33 -0700 (PDT) Subject: Re: [PATCH 26/59] KVM: arm64: nv: Respect the virtual HCR_EL2.NV bit setting To: Julien Thierry , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org References: <20190621093843.220980-1-marc.zyngier@arm.com> <20190621093843.220980-27-marc.zyngier@arm.com> <8ad1b436-9325-2abb-648d-2cd3a3c9b113@arm.com> From: Marc Zyngier Openpgp: preference=signencrypt Autocrypt: addr=marc.zyngier@arm.com; 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Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <8ad1b436-9325-2abb-648d-2cd3a3c9b113@arm.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190703_093136_320199_A13F975B X-CRM114-Status: GOOD ( 20.90 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Suzuki K Poulose , Andre Przywara , Christoffer Dall , Dave Martin , James Morse , Jintack Lim Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 26/06/2019 06:31, Julien Thierry wrote: > > > On 06/21/2019 10:38 AM, Marc Zyngier wrote: >> From: Jintack Lim >> >> Forward traps due to HCR_EL2.NV bit to the virtual EL2 if they are not >> coming from the virtual EL2 and the virtual HCR_EL2.NV bit is set. >> >> In addition to EL2 register accesses, setting NV bit will also make EL12 >> register accesses trap to EL2. To emulate this for the virtual EL2, >> forword traps due to EL12 register accessses to the virtual EL2 if the >> virtual HCR_EL2.NV bit is set. >> >> This is for recursive nested virtualization. >> >> Signed-off-by: Jintack Lim >> [Moved code to emulate-nested.c] >> Signed-off-by: Christoffer Dall >> Signed-off-by: Marc Zyngier >> --- >> arch/arm64/include/asm/kvm_arm.h | 1 + >> arch/arm64/include/asm/kvm_nested.h | 2 ++ >> arch/arm64/kvm/emulate-nested.c | 28 ++++++++++++++++++++++++++++ >> arch/arm64/kvm/handle_exit.c | 6 ++++++ >> arch/arm64/kvm/sys_regs.c | 18 ++++++++++++++++++ >> 5 files changed, 55 insertions(+) >> >> diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h >> index 48e15af2bece..d21486274eeb 100644 >> --- a/arch/arm64/include/asm/kvm_arm.h >> +++ b/arch/arm64/include/asm/kvm_arm.h >> @@ -24,6 +24,7 @@ >> >> /* Hyp Configuration Register (HCR) bits */ >> #define HCR_FWB (UL(1) << 46) >> +#define HCR_NV (UL(1) << 42) >> #define HCR_API (UL(1) << 41) >> #define HCR_APK (UL(1) << 40) >> #define HCR_TEA (UL(1) << 37) >> diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h >> index 645e5e11b749..61e71d0d2151 100644 >> --- a/arch/arm64/include/asm/kvm_nested.h >> +++ b/arch/arm64/include/asm/kvm_nested.h >> @@ -11,5 +11,7 @@ static inline bool nested_virt_in_use(const struct kvm_vcpu *vcpu) >> } >> >> int handle_wfx_nested(struct kvm_vcpu *vcpu, bool is_wfe); >> +extern bool forward_traps(struct kvm_vcpu *vcpu, u64 control_bit); >> +extern bool forward_nv_traps(struct kvm_vcpu *vcpu); >> >> #endif /* __ARM64_KVM_NESTED_H */ >> diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c >> index f829b8b04dc8..c406fd688b9f 100644 >> --- a/arch/arm64/kvm/emulate-nested.c >> +++ b/arch/arm64/kvm/emulate-nested.c >> @@ -24,6 +24,27 @@ >> >> #include "trace.h" >> >> +bool forward_traps(struct kvm_vcpu *vcpu, u64 control_bit) > > Should this one be static? $ git grep forward_traps arch/arm64/include/asm/kvm_nested.h:extern bool forward_traps(struct kvm_vcpu *vcpu, u64 control_bit); arch/arm64/kvm/emulate-nested.c:bool forward_traps(struct kvm_vcpu *vcpu, u64 control_bit) arch/arm64/kvm/emulate-nested.c: return forward_traps(vcpu, HCR_NV); arch/arm64/kvm/sys_regs.c: return forward_traps(vcpu, HCR_AT); arch/arm64/kvm/sys_regs.c: return forward_traps(vcpu, HCR_TTLB); arch/arm64/kvm/sys_regs.c: return forward_traps(vcpu, HCR_NV1); I guess not. > >> +{ >> + bool control_bit_set; >> + >> + if (!nested_virt_in_use(vcpu)) >> + return false; >> + >> + control_bit_set = __vcpu_sys_reg(vcpu, HCR_EL2) & control_bit; >> + if (!vcpu_mode_el2(vcpu) && control_bit_set) { >> + kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu)); >> + return true; >> + } >> + return false; >> +} >> + >> +bool forward_nv_traps(struct kvm_vcpu *vcpu) >> +{ >> + return forward_traps(vcpu, HCR_NV); >> +} >> + >> + >> /* This is borrowed from get_except_vector in inject_fault.c */ >> static u64 get_el2_except_vector(struct kvm_vcpu *vcpu, >> enum exception_type type) >> @@ -55,6 +76,13 @@ void kvm_emulate_nested_eret(struct kvm_vcpu *vcpu) >> u64 spsr, elr, mode; >> bool direct_eret; >> >> + /* >> + * Forward this trap to the virtual EL2 if the virtual >> + * HCR_EL2.NV bit is set and this is coming from !EL2. >> + */ >> + if (forward_nv_traps(vcpu)) >> + return; >> + >> /* >> * Going through the whole put/load motions is a waste of time >> * if this is a VHE guest hypervisor returning to its own >> diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c >> index 39602a4c1d61..7e8b1ec1d251 100644 >> --- a/arch/arm64/kvm/handle_exit.c >> +++ b/arch/arm64/kvm/handle_exit.c >> @@ -72,6 +72,12 @@ static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run) >> { >> int ret; >> >> + /* >> + * Forward this trapped smc instruction to the virtual EL2. >> + */ >> + if ((vcpu_read_sys_reg(vcpu, HCR_EL2) & HCR_TSC) && forward_nv_traps(vcpu)) > > Not sure I understand why this would be only when the guest hyp also has > NV set. > > If the guest hyp requested to trap smc instructions and that we received > one while in vel1, shouldn't we always forward it to the guest hyp to > let it implement the smc response the way it wants? There is a small difference, but I'm not sure it matters: If EL3 is not implemented, SMC UNDEFs at EL1 unless NV is set. So we know here that our guest is running a guest hypervisor. But does it change a thing? I need to think about it again... :-( M. -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel