From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f73.google.com (mail-wr1-f73.google.com [209.85.221.73]) (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 BD1C82FEE31 for ; Thu, 17 Jul 2025 16:27:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752769672; cv=none; b=c5wAgQPRC/8bxleRlQbJEe11U67afXC/ZfQUKJt3K4Z6DdbFObJpwSlTJaBnP6DpTALbdAvTcUFNdyJ6PmWijxag8U4dWrrGZh3tkBt//BJovIlDwHv0kQ4suXJ93l6tJo4CfjVboirVzsqVEmpXGhTCORzv0mQwY9v4gL8PV+s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752769672; c=relaxed/simple; bh=zEZkLi/zufUM9bTMjQStV1DSpFIHKsECtzBWN+Saz3c=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=CP0xp42Rln0S7VV+r4UtX+5rQK3PVoeeVY+2FpZoJmDaWbpi9EQ71WHt4b0mdbHTwrh4SX0ErtQAOYU6FQpxCMToe9RaOsg7E/Mo1RxYdaCed+PLMU5yiryucfb2RdhVm0XdYU2nAdqQCQhCPLEpaEeWFp0IeTqBgocJbf7Zu3k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--tabba.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=Gv6AZ4a+; arc=none smtp.client-ip=209.85.221.73 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=flex--tabba.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Gv6AZ4a+" Received: by mail-wr1-f73.google.com with SMTP id ffacd0b85a97d-3a4eee2398bso555219f8f.1 for ; Thu, 17 Jul 2025 09:27:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1752769669; x=1753374469; darn=lists.linux.dev; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=FLr2IgfKpLCEHT7MXIG6C0hRgCJ9BMJYV3UvbtKXymU=; b=Gv6AZ4a+dsrt3/oOt2rx0xFuJu+eFq5XQiQzyOOiJjEy2ukgPiRPVIqmClMEGEcAwI T1HB0+q1+rWt+Ykx2bZTUqRdP3Yo3X5yry3BBHoMfQyCm4cNKGZqJ3iR/sckm/RC0s/0 43yr/WFAr0a93OJiLefAndnFtB0oC3RJ4wc/+/DrLq5RmVh4kEGwDCQA95JFm88dewku Q6UBIyieHxOw8fDbV+oAnGOjCsI5rh/+H2sw1bmOMiqx0FSmJDdHZn4xwhIohEVDUwVi NZTXlO+IS7VX/oWFlpj7RUg82qDq6lOlHw1e8vGDsg/1Ye3d+Vw7XvEFsXucAPFq9/mi T2AQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1752769669; x=1753374469; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=FLr2IgfKpLCEHT7MXIG6C0hRgCJ9BMJYV3UvbtKXymU=; b=YlvAMRj2F8k4cNSCtjiGALwfThzBLUb2+Skus8t14CaCTAF1RAN1QfZFzjvYq5HNw7 nabCPhlcM4ZGsleX6WQX7w6jVhEaWLDkwy5h2sdi5l/vCfIqoHYigcMCRmHe6wPejW94 3433vV7rA+ZESwIEnvG/wk71KZLkRXWe0AHBwj6XpqMakKXUDhSFoitK6z/ooA26mBHQ EeZwZfyggUOdFbh/P02RMclV8AvwumPEez5wLLW9nUE0Bmo/vCZcCvpEkGuQN00yefj3 1z4VYVOMUAExx1u+Bs1Bwv+brVSPOE83pAp2065N7jfCQk9+gWiSaOk000+Mifgz4kXr yxIQ== X-Forwarded-Encrypted: i=1; AJvYcCUKvUONAskr5ptuA5+7XOMAIq6Degw+nUod42n7kGwEuI8NNEhPXxlX417wS3NoTwtWzQsU1vw=@lists.linux.dev X-Gm-Message-State: AOJu0YyhlnvCKmuMXkPgaoP/2UpC07dwmsBHsip2XF6GDIqr6NYImqAk 7D2t1S3cyW9bHPJejPP4iev0D2jmrHQ2D4UdeWYqwT89iq2Chb2eIfnCtRByVb5BXpFSw/dO11l Y0g== X-Google-Smtp-Source: AGHT+IGLGRNOwWdU0sarMvh/CV/xZw5fHmBfiAXJxNl/bH62ly67wunlKYsYQUCgrzb+O9vFJnxucVGfVg== X-Received: from wrrv11.prod.google.com ([2002:a5d:43cb:0:b0:3a5:751c:a327]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6000:2811:b0:3a5:8565:44d1 with SMTP id ffacd0b85a97d-3b60dd78e32mr4493555f8f.25.1752769668932; Thu, 17 Jul 2025 09:27:48 -0700 (PDT) Date: Thu, 17 Jul 2025 17:27:26 +0100 In-Reply-To: <20250717162731.446579-1-tabba@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250717162731.446579-1-tabba@google.com> X-Mailer: git-send-email 2.50.0.727.gbf7dc18ff4-goog Message-ID: <20250717162731.446579-17-tabba@google.com> Subject: [PATCH v15 16/21] KVM: arm64: Handle guest_memfd-backed guest page faults From: Fuad Tabba To: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev Cc: pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, seanjc@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.org, akpm@linux-foundation.org, xiaoyao.li@intel.com, yilun.xu@intel.com, chao.p.peng@linux.intel.com, jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com, isaku.yamahata@intel.com, mic@digikod.net, vbabka@suse.cz, vannapurve@google.com, ackerleytng@google.com, mail@maciej.szmigiero.name, david@redhat.com, michael.roth@amd.com, wei.w.wang@intel.com, liam.merwick@oracle.com, isaku.yamahata@gmail.com, kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com, steven.price@arm.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_tsoni@quicinc.com, quic_svaddagi@quicinc.com, quic_cvanscha@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, catalin.marinas@arm.com, james.morse@arm.com, yuzenghui@huawei.com, oliver.upton@linux.dev, maz@kernel.org, will@kernel.org, qperret@google.com, keirf@google.com, roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org, jgg@nvidia.com, rientjes@google.com, jhubbard@nvidia.com, fvdl@google.com, hughd@google.com, jthoughton@google.com, peterx@redhat.com, pankaj.gupta@amd.com, ira.weiny@intel.com, tabba@google.com Content-Type: text/plain; charset="UTF-8" Add arm64 architecture support for handling guest page faults on memory slots backed by guest_memfd. This change introduces a new function, gmem_abort(), which encapsulates the fault handling logic specific to guest_memfd-backed memory. The kvm_handle_guest_abort() entry point is updated to dispatch to gmem_abort() when a fault occurs on a guest_memfd-backed memory slot (as determined by kvm_slot_has_gmem()). Until guest_memfd gains support for huge pages, the fault granule for these memory regions is restricted to PAGE_SIZE. Reviewed-by: Gavin Shan Reviewed-by: James Houghton Signed-off-by: Fuad Tabba --- arch/arm64/kvm/mmu.c | 86 ++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 83 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index b3eacb400fab..8c82df80a835 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1512,6 +1512,82 @@ static void adjust_nested_fault_perms(struct kvm_s2_trans *nested, *prot |= kvm_encode_nested_level(nested); } +#define KVM_PGTABLE_WALK_MEMABORT_FLAGS (KVM_PGTABLE_WALK_HANDLE_FAULT | KVM_PGTABLE_WALK_SHARED) + +static int gmem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, + struct kvm_s2_trans *nested, + struct kvm_memory_slot *memslot, bool is_perm) +{ + bool write_fault, exec_fault, writable; + enum kvm_pgtable_walk_flags flags = KVM_PGTABLE_WALK_MEMABORT_FLAGS; + enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R; + struct kvm_pgtable *pgt = vcpu->arch.hw_mmu->pgt; + unsigned long mmu_seq; + struct page *page; + struct kvm *kvm = vcpu->kvm; + void *memcache; + kvm_pfn_t pfn; + gfn_t gfn; + int ret; + + ret = prepare_mmu_memcache(vcpu, true, &memcache); + if (ret) + return ret; + + if (nested) + gfn = kvm_s2_trans_output(nested) >> PAGE_SHIFT; + else + gfn = fault_ipa >> PAGE_SHIFT; + + write_fault = kvm_is_write_fault(vcpu); + exec_fault = kvm_vcpu_trap_is_exec_fault(vcpu); + + VM_WARN_ON_ONCE(write_fault && exec_fault); + + mmu_seq = kvm->mmu_invalidate_seq; + /* Pairs with the smp_wmb() in kvm_mmu_invalidate_end(). */ + smp_rmb(); + + ret = kvm_gmem_get_pfn(kvm, memslot, gfn, &pfn, &page, NULL); + if (ret) { + kvm_prepare_memory_fault_exit(vcpu, fault_ipa, PAGE_SIZE, + write_fault, exec_fault, false); + return ret; + } + + writable = !(memslot->flags & KVM_MEM_READONLY); + + if (nested) + adjust_nested_fault_perms(nested, &prot, &writable); + + if (writable) + prot |= KVM_PGTABLE_PROT_W; + + if (exec_fault || + (cpus_have_final_cap(ARM64_HAS_CACHE_DIC) && + (!nested || kvm_s2_trans_executable(nested)))) + prot |= KVM_PGTABLE_PROT_X; + + kvm_fault_lock(kvm); + if (mmu_invalidate_retry(kvm, mmu_seq)) { + ret = -EAGAIN; + goto out_unlock; + } + + ret = KVM_PGT_FN(kvm_pgtable_stage2_map)(pgt, fault_ipa, PAGE_SIZE, + __pfn_to_phys(pfn), prot, + memcache, flags); + +out_unlock: + kvm_release_faultin_page(kvm, page, !!ret, writable); + kvm_fault_unlock(kvm); + + if (writable && !ret) + mark_page_dirty_in_slot(kvm, memslot, gfn); + + return ret != -EAGAIN ? ret : 0; +} + static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, struct kvm_s2_trans *nested, struct kvm_memory_slot *memslot, unsigned long hva, @@ -1536,7 +1612,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R; struct kvm_pgtable *pgt; struct page *page; - enum kvm_pgtable_walk_flags flags = KVM_PGTABLE_WALK_HANDLE_FAULT | KVM_PGTABLE_WALK_SHARED; + enum kvm_pgtable_walk_flags flags = KVM_PGTABLE_WALK_MEMABORT_FLAGS; if (fault_is_perm) fault_granule = kvm_vcpu_trap_get_perm_fault_granule(vcpu); @@ -1961,8 +2037,12 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu) VM_WARN_ON_ONCE(kvm_vcpu_trap_is_permission_fault(vcpu) && !write_fault && !kvm_vcpu_trap_is_exec_fault(vcpu)); - ret = user_mem_abort(vcpu, fault_ipa, nested, memslot, hva, - esr_fsc_is_permission_fault(esr)); + if (kvm_slot_has_gmem(memslot)) + ret = gmem_abort(vcpu, fault_ipa, nested, memslot, + esr_fsc_is_permission_fault(esr)); + else + ret = user_mem_abort(vcpu, fault_ipa, nested, memslot, hva, + esr_fsc_is_permission_fault(esr)); if (ret == 0) ret = 1; out: -- 2.50.0.727.gbf7dc18ff4-goog