From patchwork Fri Jun 5 16:18:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 11589969 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 62A48618 for ; Fri, 5 Jun 2020 16:19:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3CBB6207D3 for ; Fri, 5 Jun 2020 16:19:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591373940; bh=paJXf48AWQH6tw11YLkNIpuHunscwji3xlYKrNSY0oo=; h=From:To:Cc:Subject:Date:List-ID:From; b=D29rxFjRu2VnMthbcC20rXaaVQutUKOeXkMGXtg6b80umqW5GW9JlJrud0BGv0yaA EP6XgCW5qZOaYfIjPSn25SGIiyKYdGVp69U/bT+xpbsEUDFxTvf+jD7gJBm3k2kXkm wJfIZFc3rlK5fg5zGoKwB0mY3dYNFrBrqHhrae5w= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726090AbgFEQS7 (ORCPT ); Fri, 5 Jun 2020 12:18:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:56160 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726024AbgFEQS6 (ORCPT ); Fri, 5 Jun 2020 12:18:58 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 985CB206DB; Fri, 5 Jun 2020 16:18:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591373937; bh=paJXf48AWQH6tw11YLkNIpuHunscwji3xlYKrNSY0oo=; h=From:To:Cc:Subject:Date:From; b=Qw60EwTzazbCTcePt+nm7ifIpHUNoIxiUj2mmFBkwGDmtc3RNXQuLeGnFhtfSD6H/ KGeyiVDYs0Cmx/cIVyQ8nzbE4iWSn/EkqeGk3ePL3mTYMXlHdOzuFkkHX9+a8I1X7L WuIwLjVGJPwOvsP4HtcuxWjk8wBt3x9iZCO3h6ug= Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jhF3Y-000YzD-2R; Fri, 05 Jun 2020 17:18:56 +0100 From: Marc Zyngier To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Cc: James Morse , Julien Thierry , Suzuki K Poulose , Mark Rutland , kernel-team@android.com, Andrew Scull Subject: [PATCH] KVM: arm64: Remove host_cpu_context member from vcpu structure Date: Fri, 5 Jun 2020 17:18:47 +0100 Message-Id: <20200605161847.1316354-1-maz@kernel.org> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, mark.rutland@arm.com, kernel-team@android.com, ascull@google.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org For very long, we have kept this pointer back to the per-cpu host state, despite having working per-cpu accessors at EL2 for some time now. Recent investigations have shown that this pointer is easy to abuse in preemptible context, which is a sure sign that it would better be gone. Not to mention that a per-cpu pointer is faster to access at all times. Reported-by: Andrew Scull Signed-off-by: Marc Zyngier --- This patch goes on top of the PtrAuth rework that I have previously posted, and make sures it is harder to fall into the same trap. arch/arm64/include/asm/kvm_host.h | 3 --- arch/arm64/kvm/arm.c | 3 --- arch/arm64/kvm/hyp/debug-sr.c | 4 ++-- arch/arm64/kvm/hyp/switch.c | 6 +++--- arch/arm64/kvm/hyp/sysreg-sr.c | 6 ++++-- arch/arm64/kvm/pmu.c | 8 ++------ 6 files changed, 11 insertions(+), 19 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 59029e90b557..ada1faa92211 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -284,9 +284,6 @@ struct kvm_vcpu_arch { struct kvm_guest_debug_arch vcpu_debug_state; struct kvm_guest_debug_arch external_debug_state; - /* Pointer to host CPU context */ - struct kvm_cpu_context *host_cpu_context; - struct thread_info *host_thread_info; /* hyp VA */ struct user_fpsimd_state *host_fpsimd_state; /* hyp VA */ diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 14b747266607..6ddaa23ef346 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -340,10 +340,8 @@ void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) { int *last_ran; - kvm_host_data_t *cpu_data; last_ran = this_cpu_ptr(vcpu->kvm->arch.last_vcpu_ran); - cpu_data = this_cpu_ptr(&kvm_host_data); /* * We might get preempted before the vCPU actually runs, but @@ -355,7 +353,6 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) } vcpu->cpu = cpu; - vcpu->arch.host_cpu_context = &cpu_data->host_ctxt; kvm_vgic_load(vcpu); kvm_timer_vcpu_load(vcpu); diff --git a/arch/arm64/kvm/hyp/debug-sr.c b/arch/arm64/kvm/hyp/debug-sr.c index 0fc9872a1467..e95af204fec7 100644 --- a/arch/arm64/kvm/hyp/debug-sr.c +++ b/arch/arm64/kvm/hyp/debug-sr.c @@ -185,7 +185,7 @@ void __hyp_text __debug_switch_to_guest(struct kvm_vcpu *vcpu) if (!(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY)) return; - host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context); + host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt; guest_ctxt = &vcpu->arch.ctxt; host_dbg = &vcpu->arch.host_debug_state.regs; guest_dbg = kern_hyp_va(vcpu->arch.debug_ptr); @@ -207,7 +207,7 @@ void __hyp_text __debug_switch_to_host(struct kvm_vcpu *vcpu) if (!(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY)) return; - host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context); + host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt; guest_ctxt = &vcpu->arch.ctxt; host_dbg = &vcpu->arch.host_debug_state.regs; guest_dbg = kern_hyp_va(vcpu->arch.debug_ptr); diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c index fc09c3dfa466..fc671426c14b 100644 --- a/arch/arm64/kvm/hyp/switch.c +++ b/arch/arm64/kvm/hyp/switch.c @@ -544,7 +544,7 @@ static bool __hyp_text __hyp_handle_ptrauth(struct kvm_vcpu *vcpu) return false; } - ctxt = kern_hyp_va(vcpu->arch.host_cpu_context); + ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt; __ptrauth_save_key(ctxt->sys_regs, APIA); __ptrauth_save_key(ctxt->sys_regs, APIB); __ptrauth_save_key(ctxt->sys_regs, APDA); @@ -715,7 +715,7 @@ static int __kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu) struct kvm_cpu_context *guest_ctxt; u64 exit_code; - host_ctxt = vcpu->arch.host_cpu_context; + host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt; host_ctxt->__hyp_running_vcpu = vcpu; guest_ctxt = &vcpu->arch.ctxt; @@ -820,7 +820,7 @@ int __hyp_text __kvm_vcpu_run_nvhe(struct kvm_vcpu *vcpu) vcpu = kern_hyp_va(vcpu); - host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context); + host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt; host_ctxt->__hyp_running_vcpu = vcpu; guest_ctxt = &vcpu->arch.ctxt; diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c index 6d2df9fe0b5d..143d7b7358f2 100644 --- a/arch/arm64/kvm/hyp/sysreg-sr.c +++ b/arch/arm64/kvm/hyp/sysreg-sr.c @@ -265,12 +265,13 @@ void __hyp_text __sysreg32_restore_state(struct kvm_vcpu *vcpu) */ void kvm_vcpu_load_sysregs(struct kvm_vcpu *vcpu) { - struct kvm_cpu_context *host_ctxt = vcpu->arch.host_cpu_context; struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt; + struct kvm_cpu_context *host_ctxt; if (!has_vhe()) return; + host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt; __sysreg_save_user_state(host_ctxt); /* @@ -301,12 +302,13 @@ void kvm_vcpu_load_sysregs(struct kvm_vcpu *vcpu) */ void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu) { - struct kvm_cpu_context *host_ctxt = vcpu->arch.host_cpu_context; struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt; + struct kvm_cpu_context *host_ctxt; if (!has_vhe()) return; + host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt; deactivate_traps_vhe_put(); __sysreg_save_el1_state(guest_ctxt); diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c index e71d00bb5271..ebf8509b418b 100644 --- a/arch/arm64/kvm/pmu.c +++ b/arch/arm64/kvm/pmu.c @@ -163,15 +163,13 @@ static void kvm_vcpu_pmu_disable_el0(unsigned long events) */ void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu) { - struct kvm_cpu_context *host_ctxt; struct kvm_host_data *host; u32 events_guest, events_host; if (!has_vhe()) return; - host_ctxt = vcpu->arch.host_cpu_context; - host = container_of(host_ctxt, struct kvm_host_data, host_ctxt); + host = __hyp_this_cpu_ptr(kvm_host_data); events_guest = host->pmu_events.events_guest; events_host = host->pmu_events.events_host; @@ -184,15 +182,13 @@ void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu) */ void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu) { - struct kvm_cpu_context *host_ctxt; struct kvm_host_data *host; u32 events_guest, events_host; if (!has_vhe()) return; - host_ctxt = vcpu->arch.host_cpu_context; - host = container_of(host_ctxt, struct kvm_host_data, host_ctxt); + host = __hyp_this_cpu_ptr(kvm_host_data); events_guest = host->pmu_events.events_guest; events_host = host->pmu_events.events_host;