From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f50.google.com (mail-wm1-f50.google.com [209.85.128.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2616D4B0495 for ; Mon, 19 Oct 2026 10:01:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.50 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792404103; cv=none; b=o699aMuAxU7c1Lk7fVTMQF7AtaEN75gQmIWWOHaBcoZQ89hcBebAOVG42sNIZbgAQFXKVhAQf8SiDqujIPX2Vet86tpXE2P/JfkwgOGXp0QwOW53JrnvYLKeU0FCCnNpmwuYm+v4bFvUO9aHW5RWD7zQOgar4xisrxYT/Af15GU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792404103; c=relaxed/simple; bh=OKUR09aYo4+hANOYcFiQPjrHiwdQlPDgUbuHfofpoeU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=fF8+6yVGgQdNL0vzNfoDNtZP94O74ikH1pjRRoKuJg7++i2KOlk8sGDA2Jk9PRwhOAZOCH1won4TYmxHR1d8DS9papkxN3LaAHksd+eX8mZZJRCPOKuujAUhkubMV89NltKLqqRimdByBMS2/48ZkTpZoFcWN4TycsoDvzCC9t8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=hCACPEcN; arc=none smtp.client-ip=209.85.128.50 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="hCACPEcN" Received: by mail-wm1-f50.google.com with SMTP id 5b1f17b1804b1-4a1e3b87ac5so8683475e9.1 for ; Mon, 19 Oct 2026 03:01:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1792404100; x=1793008900; darn=lists.linux.dev; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=JvNBlD/JZ8hRBqmq1fD5HU1ZQqr0SeMst3WentULn88=; b=hCACPEcNgFCxGdpJbyAwkSRA3/0ehoHNsInYPCfRHy/f3ek8jbv0gioBPdpCUmMVN0 NaJRH/DhIAFI82ehCxIKlWdLAygu5NmspyMKnYskky+KZf8/AMjGtleJvZDSOvHnHEue Ep3k1w/aJ6f6r/mWYZo2q+0h/SdLsEpA+VncrjH4VIMDSRZCp4C0mzfYP7RABnf16sjk MIBXkR4UB2ub9owixXkYj/d/t5JF2RSv79Vq+qe6+csHN+ImU9nkVLLicMOn7X6KXIB9 EqNfiUeUqJ4R07FLwu2zOnSEJdLi8tGxAhUADzL/E+JjaZlguLfVsWEsY2vU/ZztUsHT vW8w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1792404100; x=1793008900; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=JvNBlD/JZ8hRBqmq1fD5HU1ZQqr0SeMst3WentULn88=; b=zuKjXT8ZQNPrjELFhltBnYXL32sMhrKjW+Wc3IgkiZBhFDeVomGUanqhm44TJR/s4x jxaD+PTX+LXMYlADAzjZF00MEyfUspfHX7LfOo8JvpJdwapNg3LUYaXacDxQ9bhlgCGr /uJs9NDZ1dC9iWZ9WWwXVf/1/GmDuje5uvr5Ha7iBrr2Q1sGBqaCgWjAmFzbbF3DVzFR 0ChfapH7ozJXlEQBqvnwhAJnwr3GBfH6JwflLXrSz7pK/5H/nlrPRpZVWRyoliWEIkSL o+ufKRMCcJCaigd9zUK4RGcveDhumDE1QPTk6sYfkMpsjXzNbfVuYMDgvUlpjqQRzFzy hFdw== X-Forwarded-Encrypted: i=1; AKwUvBycaZ54MvgnIcRxZ7JqeItd6dTJirdDoRykIGkSLAV1xJaTfg7SNtlfeTiC157MqtiqB7vLFZQ=@lists.linux.dev X-Gm-Message-State: AFq9FYJqUMHXEAIeru5VQ5C80Nnb3SlxgG+s3iLd1LYFs/EYugawNPXd pgYvJ4U+rR0BpZPXQ68a/Fd0j8BQaHHNTA3q51pmcIU7sYa8yRblbYvH0rxa0KaIkvHDF6Qap2A 9aQMwnQ== X-Gm-Gg: AYBFou0JYExbSfkDMOHzQMMiG4AcxfXOlrB+hr5DWSsOczSFfmRZhpHSVcP2l4I7L7Q taDTnSSgJ7V7HjBh24C5gZm09wk2xVoI0GhEw268Q7kbSRc8B6dnCR5532mlWwMAgszSc6Z/5Ec rJHM5GPvyOxFK2jHlC3jcyu9YtSauhgLyjcteRSfrlBPwLcPz30+C9l1HUomE2l5Z7lbT0ZwLo9 7BcoxI6RMg8i26rVYoDiT8qDHdcGA/0kwQFMsKD4rSW8yXPwsponpxTmlnhia55w1H3sVg/MD18 XiuJUPGFL6Uef7ZOl6qUTNXxPBNZMKvAFIURlvM8jNhmWBTY/i3EAEZlCHUBLntNStAfX0RLbj5 eY8PQ3WDsGHUgCPV+HYayWHCMmkjp1LwO5kTV//w9bGg/OuvArFCgBrolCqZtceTcDqKlOsVZ6x Fv1m2T0/lvECDXSd69ldNVVXVHAViRf2us+D7x4W95w0nzPfaNohe4WUP1EgEZql9x/t3vh9Trh X8YI5XGNQBzLZg6oMe6Jl8ZnLtAnG54s2tXMtq8EE4= X-Received: by 2002:a05:600c:674f:b0:4a1:7e76:d02f with SMTP id 5b1f17b1804b1-4a1d75fce45mr143600135e9.14.1792404021999; Mon, 19 Oct 2026 03:00:21 -0700 (PDT) Received: from google.com (197.183.140.34.bc.googleusercontent.com. [34.140.183.197]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a1d85f92d9sm190610495e9.4.2026.10.19.03.00.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Oct 2026 03:00:19 -0700 (PDT) Date: Mon, 19 Oct 2026 11:00:15 +0100 From: Vincent Donnefort To: Fuad Tabba Cc: Marc Zyngier , Oliver Upton , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Mark Rutland , Quentin Perret , Fuad Tabba , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] KVM: arm64: Ensure TLBs and I-cache are private to each vCPU in pKVM Message-ID: References: <20261014125510.2928306-1-fuad.tabba@linux.dev> <20261014125510.2928306-3-fuad.tabba@linux.dev> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261014125510.2928306-3-fuad.tabba@linux.dev> On Wed, Oct 14, 2026 at 01:55:10PM +0100, Fuad Tabba wrote: > All vCPUs of a VM share its VMID, so KVM flushes a physical CPU's TLBs > and I-cache for the VM whenever a different vCPU of that VM is loaded > there (vcpu_prepare_mmu()). Commit fce886a602073 ("KVM: arm64: Plumb the > pKVM MMU in KVM") moved pKVM guests, protected or not, onto the > hypervisor's stage-2 and VMID, and the host stopped flushing for them. > Nothing at EL2 flushes instead, so a vCPU can hit TLB and I-cache > entries that another vCPU of the same VM left on that CPU. > > Track the last vCPU loaded on each physical CPU in the hyp VM, and flush > at EL2 in __pkvm_vcpu_load() when it changes. > > Fixes: fce886a602073 ("KVM: arm64: Plumb the pKVM MMU in KVM") > Signed-off-by: Fuad Tabba > --- > arch/arm64/kvm/hyp/include/nvhe/pkvm.h | 3 +++ > arch/arm64/kvm/hyp/nvhe/hyp-main.c | 8 ++++++++ > arch/arm64/kvm/hyp/nvhe/pkvm.c | 21 ++++++++++++++++++--- > 3 files changed, 29 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h > index 9abfe6b7e942b..02c8fc7a10904 100644 > --- a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h > +++ b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h > @@ -54,6 +54,9 @@ struct pkvm_hyp_vm { > unsigned short refcount; > hyp_spinlock_t lock; > > + /* Per physical CPU, the vcpu_idx of the last vCPU of this VM loaded there. */ > + int *last_vcpu_ran; Unlikely to be a problem in pratice, but vcpu_idx is "unsigned int". I wonder if this shouldn't be unsigned int here too and initialised to UINT_MAX? > + > /* > * The vCPU initialised RUNNABLE: claimed under vm_table_lock, > * released only if its own init fails. > diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c > index d715aa942577e..f0b77236c871e 100644 > --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c > +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c > @@ -827,11 +827,19 @@ DEFINE_KVM_HOST_HCALL(void, __pkvm_vcpu_load, > pkvm_handle_t, handle, unsigned int, vcpu_idx, u64, hcr_el2) > { > struct pkvm_hyp_vcpu *hyp_vcpu; > + int *last_ran; > > hyp_vcpu = pkvm_load_hyp_vcpu(handle, vcpu_idx); > if (!hyp_vcpu) > return; > > + /* TLBs and I-cache are private to each vCPU, see vcpu_prepare_mmu(). */ > + last_ran = &pkvm_hyp_vcpu_to_hyp_vm(hyp_vcpu)->last_vcpu_ran[hyp_smp_processor_id()]; > + if (*last_ran != vcpu_idx) { > + __kvm_flush_cpu_context(hyp_vcpu->vcpu.arch.hw_mmu); > + *last_ran = vcpu_idx; > + } > + > if (pkvm_hyp_vcpu_is_protected(hyp_vcpu)) { > u64 dfr0 = read_sysreg(id_aa64dfr0_el1); > > diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c > index ac020d0501d2e..f18fa762746c9 100644 > --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c > +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c > @@ -489,10 +489,11 @@ static void unpin_host_vcpus(struct pkvm_hyp_vcpu *hyp_vcpus[], > } > > static void init_pkvm_hyp_vm(struct kvm *host_kvm, struct pkvm_hyp_vm *hyp_vm, > - unsigned int nr_vcpus, pkvm_handle_t handle) > + int *last_vcpu_ran, unsigned int nr_vcpus, pkvm_handle_t handle) > { > struct kvm_s2_mmu *mmu = &hyp_vm->kvm.arch.mmu; > int idx = vm_handle_to_idx(handle); > + unsigned long cpu; > > hyp_vm->kvm.arch.pkvm.handle = handle; > > @@ -512,6 +513,10 @@ static void init_pkvm_hyp_vm(struct kvm *host_kvm, struct pkvm_hyp_vm *hyp_vm, > mmu->vtcr = host_mmu.arch.mmu.vtcr; > mmu->arch = &hyp_vm->kvm.arch; > mmu->pgt = &hyp_vm->pgt; > + > + for (cpu = 0; cpu < hyp_nr_cpus; cpu++) > + last_vcpu_ran[cpu] = -1; > + hyp_vm->last_vcpu_ran = last_vcpu_ran; > } > > static int pkvm_vcpu_init_sve(struct pkvm_hyp_vcpu *hyp_vcpu, struct kvm_vcpu *host_vcpu) > @@ -887,6 +892,7 @@ int __pkvm_init_vm(struct kvm *host_kvm, void __kern *pgd_hva) > size_t vm_size, pgd_size; > unsigned int nr_vcpus; > pkvm_handle_t handle; > + int *last_vcpu_ran; > void *pgd = NULL; > int ret; > > @@ -915,13 +921,19 @@ int __pkvm_init_vm(struct kvm *host_kvm, void __kern *pgd_hva) > goto err_unpin_kvm; > } > > + last_vcpu_ran = hyp_alloc(array_size(hyp_nr_cpus, sizeof(*last_vcpu_ran))); > + if (!last_vcpu_ran) { > + ret = hyp_alloc_errno(); > + goto err_free_hyp_vm; > + } > + > ret = -ENOMEM; > > pgd = map_donated_memory_noclear(pgd_hva, pgd_size); > if (!pgd) > - goto err_free_hyp_vm; > + goto err_free_last_ran; > > - init_pkvm_hyp_vm(host_kvm, hyp_vm, nr_vcpus, handle); > + init_pkvm_hyp_vm(host_kvm, hyp_vm, last_vcpu_ran, nr_vcpus, handle); > > ret = kvm_guest_prepare_stage2(hyp_vm, pgd); > if (ret) > @@ -938,6 +950,8 @@ int __pkvm_init_vm(struct kvm *host_kvm, void __kern *pgd_hva) > kvm_guest_destroy_stage2(hyp_vm); > err_remove_mappings: > unmap_donated_memory(pgd, pgd_size); > +err_free_last_ran: > + hyp_free(last_vcpu_ran); > err_free_hyp_vm: > hyp_free(hyp_vm); > err_unpin_kvm: > @@ -1112,6 +1126,7 @@ int __pkvm_finalize_teardown_vm(pkvm_handle_t handle) > hyp_free(hyp_vcpu); > } > > + hyp_free(hyp_vm->last_vcpu_ran); > hyp_free(hyp_vm); > hyp_unpin_shared_mem(host_kvm, host_kvm + 1); > return 0; > -- > 2.39.5 >