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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D1DC2C433FE for ; Mon, 29 Nov 2021 21:46:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232471AbhK2Vtr (ORCPT ); Mon, 29 Nov 2021 16:49:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49860 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232291AbhK2Vrq (ORCPT ); Mon, 29 Nov 2021 16:47:46 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C2C49C091D22 for ; Mon, 29 Nov 2021 12:06:53 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 8AD7DB815FE for ; Mon, 29 Nov 2021 20:06:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3BCC1C53FD1; Mon, 29 Nov 2021 20:06:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1638216411; bh=revNVqtiu+mMGd8sw9pvXnutQlvPit8tuWd9vnCjHW8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QCxa71LfezMgLgmBMXiE/8tW8ZyOqpuOFAImsYj7oQ8aSeIBg7Llz8SYtp1kJ3LGo 8NNmmMGliwSDDedPeZpy7xklUJkK6vOhXNH0C94SVrQf4YmxKAA6kQ7KHTKLDdZmOO +fJzWJqJVLWoVWJPd0Rm3mQDLV4Ipfdei1eY0pbytTIoxofriRyDpi0+To4bElFr2M pnoXW4qxd9UTlBp3y8vtSHMyY9LEf7ZDTuYo5ubF7QZJuQ7L0aCW2Z+cydNtB1/Lxl KgpGkAwWr7XW8nZJrtI04rAWMfgyriWgFi936ly09eCNdfsu8sqKi2E1gOJ1EwzUJL VUZFUh7hNekgg== Received: from sofa.misterjones.org ([185.219.108.64] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1mrmrJ-008gvR-CC; Mon, 29 Nov 2021 20:02:41 +0000 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org Cc: Andre Przywara , Christoffer Dall , Jintack Lim , Haibo Xu , Ganapatrao Kulkarni , James Morse , Suzuki K Poulose , Alexandru Elisei , kernel-team@android.com Subject: [PATCH v5 69/69] KVM: arm64: nv: Fast-track EL1 TLBIs for VHE guests Date: Mon, 29 Nov 2021 20:01:50 +0000 Message-Id: <20211129200150.351436-70-maz@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20211129200150.351436-1-maz@kernel.org> References: <20211129200150.351436-1-maz@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, andre.przywara@arm.com, christoffer.dall@arm.com, jintack@cs.columbia.edu, haibo.xu@linaro.org, gankulkarni@os.amperecomputing.com, james.morse@arm.com, suzuki.poulose@arm.com, alexandru.elisei@arm.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Due to the way ARMv8.4-NV suppresses traps when accessing EL2 system registers, we can't track when the guest changes its HCR_EL2.TGE setting. This means we always trap EL1 TLBIs, even if they don't affect any guest. This obviously has a huge impact on performance, as we handle TLBI traps as a normal exit, and a normal VHE host issues thousands of TLBIs when booting (and quite a few when running userspace). A cheap way to reduce the overhead is to handle the limited case of {E2H,TGE}=={1,1} as a guest fixup, as we already have the right mmu configuration in place. Just execute the decoded instruction right away and return to the guest. Signed-off-by: Marc Zyngier --- arch/arm64/kvm/hyp/vhe/switch.c | 43 ++++++++++++++++++++++++++++++++- arch/arm64/kvm/hyp/vhe/tlb.c | 6 +++-- arch/arm64/kvm/sys_regs.c | 25 ++++++------------- 3 files changed, 54 insertions(+), 20 deletions(-) diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c index 6cbe6a89dbdb..fa2fd7e911b2 100644 --- a/arch/arm64/kvm/hyp/vhe/switch.c +++ b/arch/arm64/kvm/hyp/vhe/switch.c @@ -162,6 +162,47 @@ void deactivate_traps_vhe_put(struct kvm_vcpu *vcpu) __deactivate_traps_common(vcpu); } +static bool kvm_hyp_handle_tlbi_el1(struct kvm_vcpu *vcpu, u64 *exit_code) +{ + u32 instr; + u64 val; + + /* + * Ideally, we would never trap on EL1 TLB invalidations when the + * guest's HCR_EL2.{E2H,TGE} == {1,1}. But "thanks" to ARMv8.4, we + * don't trap writes to HCR_EL2, meaning that we can't track + * changes to the virtual TGE bit. So we leave HCR_EL2.TTLB set on + * the host. Oopsie... + * + * In order to speed-up EL1 TLBIs from the vEL2 guest when TGE is + * set, try and handle these invalidation as quickly as possible, + * without fully exiting (unless this needs forwarding). + */ + if (!enhanced_nested_virt_in_use(vcpu) || + !vcpu_mode_el2(vcpu) || + (__vcpu_sys_reg(vcpu, HCR_EL2) & (HCR_E2H | HCR_TGE)) != (HCR_E2H | HCR_TGE)) + return false; + + instr = esr_sys64_to_sysreg(kvm_vcpu_get_esr(vcpu)); + if (sys_reg_Op0(instr) != TLBI_Op0 || + sys_reg_Op1(instr) != TLBI_Op1_EL1) + return false; + + val = vcpu_get_reg(vcpu, kvm_vcpu_sys_get_rt(vcpu)); + __kvm_tlb_el1_instr(NULL, val, instr); + __kvm_skip_instr(vcpu); + + return true; +} + +static bool kvm_hyp_handle_sysreg_vhe(struct kvm_vcpu *vcpu, u64 *exit_code) +{ + if (kvm_hyp_handle_tlbi_el1(vcpu, exit_code)) + return true; + + return kvm_hyp_handle_sysreg(vcpu, exit_code); +} + static bool kvm_hyp_handle_eret(struct kvm_vcpu *vcpu, u64 *exit_code) { struct kvm_cpu_context *ctxt = &vcpu->arch.ctxt; @@ -210,7 +251,7 @@ static bool kvm_hyp_handle_eret(struct kvm_vcpu *vcpu, u64 *exit_code) static const exit_handler_fn hyp_exit_handlers[] = { [0 ... ESR_ELx_EC_MAX] = NULL, [ESR_ELx_EC_CP15_32] = kvm_hyp_handle_cp15_32, - [ESR_ELx_EC_SYS64] = kvm_hyp_handle_sysreg, + [ESR_ELx_EC_SYS64] = kvm_hyp_handle_sysreg_vhe, [ESR_ELx_EC_SVE] = kvm_hyp_handle_fpsimd, [ESR_ELx_EC_FP_ASIMD] = kvm_hyp_handle_fpsimd, [ESR_ELx_EC_IABT_LOW] = kvm_hyp_handle_iabt_low, diff --git a/arch/arm64/kvm/hyp/vhe/tlb.c b/arch/arm64/kvm/hyp/vhe/tlb.c index c4389db4cc22..beb162468c0b 100644 --- a/arch/arm64/kvm/hyp/vhe/tlb.c +++ b/arch/arm64/kvm/hyp/vhe/tlb.c @@ -201,7 +201,8 @@ void __kvm_tlb_el1_instr(struct kvm_s2_mmu *mmu, u64 val, u64 sys_encoding) dsb(ishst); /* Switch to requested VMID */ - __tlb_switch_to_guest(mmu, &cxt); + if (mmu) + __tlb_switch_to_guest(mmu, &cxt); /* * Execute the same instruction as the guest hypervisor did, @@ -240,5 +241,6 @@ void __kvm_tlb_el1_instr(struct kvm_s2_mmu *mmu, u64 val, u64 sys_encoding) dsb(ish); isb(); - __tlb_switch_to_host(&cxt); + if (mmu) + __tlb_switch_to_host(&cxt); } diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index e8ab052be122..acfd3c72faf6 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -2804,6 +2804,8 @@ static bool handle_tlbi_el1(struct kvm_vcpu *vcpu, struct sys_reg_params *p, const struct sys_reg_desc *r) { u32 sys_encoding = sys_insn(p->Op0, p->Op1, p->CRn, p->CRm, p->Op2); + u64 virtual_vttbr = vcpu_read_sys_reg(vcpu, VTTBR_EL2); + struct kvm_s2_mmu *mmu; /* * If we're here, this is because we've trapped on a EL1 TLBI @@ -2822,24 +2824,13 @@ static bool handle_tlbi_el1(struct kvm_vcpu *vcpu, struct sys_reg_params *p, mutex_lock(&vcpu->kvm->lock); - if ((__vcpu_sys_reg(vcpu, HCR_EL2) & (HCR_E2H | HCR_TGE)) != (HCR_E2H | HCR_TGE)) { - u64 virtual_vttbr = vcpu_read_sys_reg(vcpu, VTTBR_EL2); - struct kvm_s2_mmu *mmu; - - mmu = lookup_s2_mmu(vcpu->kvm, virtual_vttbr, HCR_VM); - if (mmu) - __kvm_tlb_el1_instr(mmu, p->regval, sys_encoding); + mmu = lookup_s2_mmu(vcpu->kvm, virtual_vttbr, HCR_VM); + if (mmu) + __kvm_tlb_el1_instr(mmu, p->regval, sys_encoding); - mmu = lookup_s2_mmu(vcpu->kvm, virtual_vttbr, 0); - if (mmu) - __kvm_tlb_el1_instr(mmu, p->regval, sys_encoding); - } else { - /* - * ARMv8.4-NV allows the guest to change TGE behind - * our back, so we always trap EL1 TLBIs from vEL2... - */ - __kvm_tlb_el1_instr(&vcpu->kvm->arch.mmu, p->regval, sys_encoding); - } + mmu = lookup_s2_mmu(vcpu->kvm, virtual_vttbr, 0); + if (mmu) + __kvm_tlb_el1_instr(mmu, p->regval, sys_encoding); mutex_unlock(&vcpu->kvm->lock); -- 2.30.2