From nobody Sun Oct 5 21:49:27 2025 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (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 56DCF2D238C for ; Tue, 29 Jul 2025 22:56:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753829765; cv=none; b=qsUsA0/6n+xuH0ZoLF3QXr+n+JD81Pz1QozYjcNjXLSgIaKd3QUY11BUbP47hR9rWRbJaB9grQKX/fqA72biSINAvnmPBwuZYkZSjgueLufZ/OrZXRXjf8khrVtUlvRXjYTFNzpYooGDh39oKffTTPFY6rtkKYLshXIBi9ZRdpg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753829765; c=relaxed/simple; bh=cJ74EwWgT8ssw15s8hHa0q/3vNUXZsCmxE/4AKvCbiA=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=T1mKiCcrrXFRHbxL8/2sc+JXbmvyTrzwiiuViUePNP9wrOcLy4l7SyMvek/CIUClmC0YajvO+5eJ/C+vKs1HAXPkRERAbFg11Qk49WSVigfVl8PsmZ8Z+mXa+OuDRBONbwe29XwgreMOWcp0m37K7fzIwq+EXNdJU/1Ms2Kc6Fc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=LAV7+ONL; arc=none smtp.client-ip=209.85.214.201 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--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="LAV7+ONL" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-2400117dd80so24904555ad.2 for ; Tue, 29 Jul 2025 15:56:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1753829763; x=1754434563; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=YGSKpa2fHnKmvhwupUv+p380hnAGu6oGZqnkqfDR1aw=; b=LAV7+ONL9oDItiV51YYBdBeZr3GUP3CA4bMPx/oWYXmLRa5sjeapVDSJNlE7Dp8nlI EU2iBzmKAJYvzXbaMWcOdsbQ4byj5GKac9kQGGnUsYqx4qtqNwp9Cq+u9DKXfhD7hsrA adkOOdgSKrUU4Ibpwhpgaer90aDNnKqhGBc8BVyCDLdbnnb67H2teBTDHZYKvlJalh0k Kbm7+OOC6OYB/5no6BUJa0w959fgEYjxD3YfCu58IUmlJv8G8w3WYRHWdFsO0uoDC4Lo SGEJaw4Um8nWYX1mzsBZOwL8I+6W9dVXRXA2cnL8laaWFr3Xw+WpiPMbrYUmToZHxexb /eqw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1753829763; x=1754434563; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=YGSKpa2fHnKmvhwupUv+p380hnAGu6oGZqnkqfDR1aw=; b=Uamyupcg9wBoj5JGZUku9LaBlU72fE/z4PEdDQww6FyqjKEH0xsJs0X2OokQFgcDuB PCOKdgIEdsdWicEBZmG/ujw8p0cQsw9f3EGjH2DFTxajHi66XrGis2eq/5MQoORXJxNN M0elf5KPl+1n2GcwvsoerpdtzSmtyZR48O4ALGimRR/9m4iZY4sfa9gqV9cO1uH+8P3a L4KTdzdfIlrXQ17MaeZ27wIJ9V4etRPZfXHLxETIp+B4mBPSads3a76jXnoF9pxRAObH jI7RXe2VdwOEuDZVJtn9U8MyQb9hqcoMK4lmKzXQJ75XiQxeXn5RBi7+VVQLYzeul8cn OWQQ== X-Forwarded-Encrypted: i=1; AJvYcCWY5sOY0Dvoj3myoB2Pru9zZ1KkH7UHPMEHUsI6dm7AqbITWyTsVZ8suppJ1ko8wDxGwtxikOHm8vNEcNw=@vger.kernel.org X-Gm-Message-State: AOJu0YzJdnfOovYxw5w8ZjAGwuI8s87HBGie/pcqbdb6jx6fKA772QFI 3Upw8hlm9uhQz84PonvVkA3fOqGEsS5+yquwBk+gNSzqvv7KYSjPmxPjGfDhKZLc8O45XmcDu2T ai9/o3w== X-Google-Smtp-Source: AGHT+IFvhUHa66DXw0WO0M1QOBisEEAf0dqbz4+FB+6ytlMqLm65KTleMot3mI0oJ4nV+lB86TE50xbpvCQ= X-Received: from pjk7.prod.google.com ([2002:a17:90b:5587:b0:31f:2a78:943]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:2301:b0:240:2ee6:fd45 with SMTP id d9443c01a7336-24096b410d1mr12990695ad.36.1753829762482; Tue, 29 Jul 2025 15:56:02 -0700 (PDT) Reply-To: Sean Christopherson Date: Tue, 29 Jul 2025 15:54:49 -0700 In-Reply-To: <20250729225455.670324-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250729225455.670324-1-seanjc@google.com> X-Mailer: git-send-email 2.50.1.552.g942d659e1b-goog Message-ID: <20250729225455.670324-19-seanjc@google.com> Subject: [PATCH v17 18/24] KVM: arm64: Handle guest_memfd-backed guest page faults From: Sean Christopherson To: Paolo Bonzini , Marc Zyngier , Oliver Upton , Sean Christopherson Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, Ira Weiny , Gavin Shan , Shivank Garg , Vlastimil Babka , Xiaoyao Li , David Hildenbrand , Fuad Tabba , Ackerley Tng , Tao Chan , James Houghton Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Fuad Tabba 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 Reviewed-by: Marc Zyngier Signed-off-by: Fuad Tabba Signed-off-by: Sean Christopherson --- 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 |=3D kvm_encode_nested_level(nested); } =20 +#define KVM_PGTABLE_WALK_MEMABORT_FLAGS (KVM_PGTABLE_WALK_HANDLE_FAULT | K= VM_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 =3D KVM_PGTABLE_WALK_MEMABORT_FLAGS; + enum kvm_pgtable_prot prot =3D KVM_PGTABLE_PROT_R; + struct kvm_pgtable *pgt =3D vcpu->arch.hw_mmu->pgt; + unsigned long mmu_seq; + struct page *page; + struct kvm *kvm =3D vcpu->kvm; + void *memcache; + kvm_pfn_t pfn; + gfn_t gfn; + int ret; + + ret =3D prepare_mmu_memcache(vcpu, true, &memcache); + if (ret) + return ret; + + if (nested) + gfn =3D kvm_s2_trans_output(nested) >> PAGE_SHIFT; + else + gfn =3D fault_ipa >> PAGE_SHIFT; + + write_fault =3D kvm_is_write_fault(vcpu); + exec_fault =3D kvm_vcpu_trap_is_exec_fault(vcpu); + + VM_WARN_ON_ONCE(write_fault && exec_fault); + + mmu_seq =3D kvm->mmu_invalidate_seq; + /* Pairs with the smp_wmb() in kvm_mmu_invalidate_end(). */ + smp_rmb(); + + ret =3D 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 =3D !(memslot->flags & KVM_MEM_READONLY); + + if (nested) + adjust_nested_fault_perms(nested, &prot, &writable); + + if (writable) + prot |=3D KVM_PGTABLE_PROT_W; + + if (exec_fault || + (cpus_have_final_cap(ARM64_HAS_CACHE_DIC) && + (!nested || kvm_s2_trans_executable(nested)))) + prot |=3D KVM_PGTABLE_PROT_X; + + kvm_fault_lock(kvm); + if (mmu_invalidate_retry(kvm, mmu_seq)) { + ret =3D -EAGAIN; + goto out_unlock; + } + + ret =3D 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 !=3D -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 =3D KVM_PGTABLE_PROT_R; struct kvm_pgtable *pgt; struct page *page; - enum kvm_pgtable_walk_flags flags =3D KVM_PGTABLE_WALK_HANDLE_FAULT | KVM= _PGTABLE_WALK_SHARED; + enum kvm_pgtable_walk_flags flags =3D KVM_PGTABLE_WALK_MEMABORT_FLAGS; =20 if (fault_is_perm) fault_granule =3D 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)); =20 - ret =3D user_mem_abort(vcpu, fault_ipa, nested, memslot, hva, - esr_fsc_is_permission_fault(esr)); + if (kvm_slot_has_gmem(memslot)) + ret =3D gmem_abort(vcpu, fault_ipa, nested, memslot, + esr_fsc_is_permission_fault(esr)); + else + ret =3D user_mem_abort(vcpu, fault_ipa, nested, memslot, hva, + esr_fsc_is_permission_fault(esr)); if (ret =3D=3D 0) ret =3D 1; out: --=20 2.50.1.552.g942d659e1b-goog