From nobody Wed Dec 17 16:11:43 2025 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id D6ADF34EF1F; Wed, 17 Dec 2025 10:13:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765966420; cv=none; b=s1bPNPA1l7CImMCiBK47TSbckYQtsCPtKh0/JsbCqwjR0ZAJ362il8tIHxI2Fj/s2oPeHkuoaDDBneInPxMNHzVBOazwh8ps2w28ipYNbJgr/HNsRzxaBssTOReznkvixMLLKCUWpm13uxGj28QK5pF6HZ7TUv8FxhACwNg6Wns= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765966420; c=relaxed/simple; bh=Y3Ve09EmIEbTl0WK46VhkKH5ggBZA0QuBsGLPFIb2I4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bNAWZ4mOwJjbbmAVmceJKm+2SSczYD9dYa5wXD22Bf5PQ1IrgdJ0H27u9x2lwuGZCZoo49Zm3fzaUgRC9CrgDcNAt4+ey6aErX1hqqekjmna3ISgzb6XTtlu0vgwzZjr4cMs5XeZeS3hvMqvOmoWBqPgH3S5D0+bmaYNpdXdI9k= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4EDAA1517; Wed, 17 Dec 2025 02:13:31 -0800 (PST) Received: from e122027.arm.com (unknown [10.57.45.201]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id CFB1D3F73B; Wed, 17 Dec 2025 02:13:33 -0800 (PST) From: Steven Price To: kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Steven Price , Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , Suzuki K Poulose , Zenghui Yu , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Joey Gouly , Alexandru Elisei , Christoffer Dall , Fuad Tabba , linux-coco@lists.linux.dev, Ganapatrao Kulkarni , Gavin Shan , Shanker Donthineni , Alper Gun , "Aneesh Kumar K . V" , Emi Kisanuki , Vishal Annapurve Subject: [PATCH v12 23/46] arm64: RMI: Add a VMID allocator for realms Date: Wed, 17 Dec 2025 10:11:00 +0000 Message-ID: <20251217101125.91098-24-steven.price@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251217101125.91098-1-steven.price@arm.com> References: <20251217101125.91098-1-steven.price@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The RMM v1.0 spec requires that the host manage the VMIDs of realm guests. Add a basic allocator and assign a unique VMID to the guest when creating the realm descriptor. Signed-off-by: Steven Price --- New patch for v12. NOTE: RMM v2.0 will remove the requirement for the host to manage VMIDs --- arch/arm64/kvm/rmi.c | 48 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c index 18edc7eeb5fa..ede6c250bcfb 100644 --- a/arch/arm64/kvm/rmi.c +++ b/arch/arm64/kvm/rmi.c @@ -600,6 +600,42 @@ static int realm_create_rd(struct kvm *kvm) return r; } =20 +/* Protects access to rmi_vmid_bitmap */ +static DEFINE_SPINLOCK(rmi_vmid_lock); +static unsigned long *rmi_vmid_bitmap; + +static int rmi_vmid_init(void) +{ + unsigned int vmid_count =3D 1 << kvm_get_vmid_bits(); + + rmi_vmid_bitmap =3D bitmap_zalloc(vmid_count, GFP_KERNEL); + if (!rmi_vmid_bitmap) { + kvm_err("%s: Couldn't allocate rmi vmid bitmap\n", __func__); + return -ENOMEM; + } + + return 0; +} + +static int rmi_vmid_reserve(void) +{ + int ret; + unsigned int vmid_count =3D 1 << kvm_get_vmid_bits(); + + spin_lock(&rmi_vmid_lock); + ret =3D bitmap_find_free_region(rmi_vmid_bitmap, vmid_count, 0); + spin_unlock(&rmi_vmid_lock); + + return ret; +} + +static void rmi_vmid_release(unsigned int vmid) +{ + spin_lock(&rmi_vmid_lock); + bitmap_release_region(rmi_vmid_bitmap, vmid, 0); + spin_unlock(&rmi_vmid_lock); +} + static int realm_unmap_private_page(struct realm *realm, unsigned long ipa, unsigned long *next_addr) @@ -903,6 +939,7 @@ static int realm_init_ipa_state(struct kvm *kvm, =20 static int realm_ensure_created(struct kvm *kvm) { + struct realm *realm =3D &kvm->arch.realm; int ret; =20 switch (kvm_realm_state(kvm)) { @@ -916,7 +953,13 @@ static int realm_ensure_created(struct kvm *kvm) return -EBUSY; } =20 + ret =3D rmi_vmid_reserve(); + if (ret < 0) + return ret; + realm->vmid =3D ret; ret =3D realm_create_rd(kvm); + if (ret) + rmi_vmid_release(realm->vmid); return ret; } =20 @@ -1307,6 +1350,8 @@ void kvm_destroy_realm(struct kvm *kvm) realm->rd =3D NULL; } =20 + rmi_vmid_release(realm->vmid); + for (i =3D 0; i < pgd_size; i +=3D RMM_PAGE_SIZE) { phys_addr_t pgd_phys =3D kvm->arch.mmu.pgd_phys + i; =20 @@ -1342,5 +1387,8 @@ void kvm_init_rmi(void) if (WARN_ON(rmi_features(0, &rmm_feat_reg0))) return; =20 + if (rmi_vmid_init()) + return; + /* Future patch will enable static branch kvm_rmi_is_available */ } --=20 2.43.0