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Sat, 17 Oct 2026 04:03:18 -0700 (PDT) From: Tharit Tangkijwanichakul To: Paolo Bonzini , Sean Christopherson Cc: Shuah Khan , Marc Zyngier , Oliver Upton , Fuad Tabba , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Anup Patel , Atish Patra , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel-mentees@lists.linux.dev, skhan@linuxfoundation.org, me@brighamcampbell.com, jkoolstra@xs4all.nl, Tharit Tangkijwanichakul Subject: [PATCH 4/5] KVM: selftests: Reserve memslot 1 for the ucall MMIO address Date: Sat, 17 Oct 2026 18:02:12 +0700 Message-ID: <20261017110213.46199-5-tharitt97@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261017110213.46199-1-tharitt97@gmail.com> References: <20261017110213.46199-1-tharitt97@gmail.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Back the ucall MMIO address with a read-only region in slot 1 when KVM_CAP_READONLY_MEM is available. Writes still exit as MMIO, while overlapping memslot creation is rejected. Start test memslots at slot 2, leaving slot 1 reserved by convention even when read-only memory is unsupported. Signed-off-by: Tharit Tangkijwanichakul --- .../testing/selftests/kvm/include/kvm_util.h | 2 +- tools/testing/selftests/kvm/lib/kvm_util.c | 19 +++++++++++++------ 2 files changed, 14 insertions(+), 7 deletions(-) diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h index 759d604d44ce..4dbb2ef332fc 100644 --- a/tools/testing/selftests/kvm/include/kvm_util.h +++ b/tools/testing/selftests/kvm/include/kvm_util.h @@ -30,7 +30,7 @@ #define KVM_DEV_PATH "/dev/kvm" #define KVM_MAX_VCPUS 512 -#define TEST_MEM_SLOT_BASE 1 +#define TEST_MEM_SLOT_BASE 2 #define NSEC_PER_SEC 1000000000L diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c index 9ddc047d5c27..73e28814a226 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -20,6 +20,7 @@ #include #define KVM_UTIL_MIN_PFN 2 +#define KVM_UCALL_MEMSLOT 1 u32 kvm_random_seed; struct kvm_random_state kvm_rng; @@ -492,6 +493,7 @@ struct kvm_vm *__vm_create(struct vm_shape shape, u32 nr_runnable_vcpus, struct userspace_mem_region *slot0; struct kvm_vm *vm; int i, flags; + gpa_t mmio_gpa; kvm_set_files_rlimit(nr_runnable_vcpus); @@ -514,14 +516,19 @@ struct kvm_vm *__vm_create(struct vm_shape shape, u32 nr_runnable_vcpus, kvm_vm_elf_load(vm, program_invocation_name); - /* - * TODO: Add proper defines to protect the library's memslots, and then - * carve out memslot1 for the ucall MMIO address. KVM treats writes to - * read-only memslots as MMIO, and creating a read-only memslot for the - * MMIO region would prevent silently clobbering the MMIO region. + /* KVM treats writes to read-only memslots as MMIO, and creating + * a read-only memslot for the MMIO region would prevent silently + * clobbering the MMIO region. */ slot0 = memslot2region(vm, 0); - ucall_init(vm, slot0->region.guest_phys_addr + slot0->region.memory_size); + mmio_gpa = slot0->region.guest_phys_addr + slot0->region.memory_size; + ucall_init(vm, mmio_gpa); + + if (vm_check_cap(vm, KVM_CAP_READONLY_MEM)) + vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, + mmio_gpa, KVM_UCALL_MEMSLOT, + vm_adjust_num_guest_pages(vm->mode, 1), + KVM_MEM_READONLY); if (kvm_random_seed != last_kvm_seed) kvm_seed_rng(kvm_random_seed); -- 2.53.0 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E5A25CCF2C7 for ; 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Sat, 17 Oct 2026 04:03:19 -0700 (PDT) Received: from x1c ([2405:9800:b670:b64b:7c65:ff3e:80ba:b06]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2e97e804dd9sm20559955ad.16.2026.10.17.04.03.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 17 Oct 2026 04:03:18 -0700 (PDT) From: Tharit Tangkijwanichakul To: Paolo Bonzini , Sean Christopherson Cc: Shuah Khan , Marc Zyngier , Oliver Upton , Fuad Tabba , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Anup Patel , Atish Patra , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel-mentees@lists.linux.dev, skhan@linuxfoundation.org, me@brighamcampbell.com, jkoolstra@xs4all.nl, Tharit Tangkijwanichakul Subject: [PATCH 4/5] KVM: selftests: Reserve memslot 1 for the ucall MMIO address Date: Sat, 17 Oct 2026 18:02:12 +0700 Message-ID: <20261017110213.46199-5-tharitt97@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261017110213.46199-1-tharitt97@gmail.com> References: <20261017110213.46199-1-tharitt97@gmail.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261017_040319_894253_C2A80538 X-CRM114-Status: GOOD ( 10.34 ) X-BeenThere: kvm-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kvm-riscv" Errors-To: kvm-riscv-bounces+kvm-riscv=archiver.kernel.org@lists.infradead.org Back the ucall MMIO address with a read-only region in slot 1 when KVM_CAP_READONLY_MEM is available. Writes still exit as MMIO, while overlapping memslot creation is rejected. Start test memslots at slot 2, leaving slot 1 reserved by convention even when read-only memory is unsupported. Signed-off-by: Tharit Tangkijwanichakul --- .../testing/selftests/kvm/include/kvm_util.h | 2 +- tools/testing/selftests/kvm/lib/kvm_util.c | 19 +++++++++++++------ 2 files changed, 14 insertions(+), 7 deletions(-) diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h index 759d604d44ce..4dbb2ef332fc 100644 --- a/tools/testing/selftests/kvm/include/kvm_util.h +++ b/tools/testing/selftests/kvm/include/kvm_util.h @@ -30,7 +30,7 @@ #define KVM_DEV_PATH "/dev/kvm" #define KVM_MAX_VCPUS 512 -#define TEST_MEM_SLOT_BASE 1 +#define TEST_MEM_SLOT_BASE 2 #define NSEC_PER_SEC 1000000000L diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c index 9ddc047d5c27..73e28814a226 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -20,6 +20,7 @@ #include #define KVM_UTIL_MIN_PFN 2 +#define KVM_UCALL_MEMSLOT 1 u32 kvm_random_seed; struct kvm_random_state kvm_rng; @@ -492,6 +493,7 @@ struct kvm_vm *__vm_create(struct vm_shape shape, u32 nr_runnable_vcpus, struct userspace_mem_region *slot0; struct kvm_vm *vm; int i, flags; + gpa_t mmio_gpa; kvm_set_files_rlimit(nr_runnable_vcpus); @@ -514,14 +516,19 @@ struct kvm_vm *__vm_create(struct vm_shape shape, u32 nr_runnable_vcpus, kvm_vm_elf_load(vm, program_invocation_name); - /* - * TODO: Add proper defines to protect the library's memslots, and then - * carve out memslot1 for the ucall MMIO address. KVM treats writes to - * read-only memslots as MMIO, and creating a read-only memslot for the - * MMIO region would prevent silently clobbering the MMIO region. + /* KVM treats writes to read-only memslots as MMIO, and creating + * a read-only memslot for the MMIO region would prevent silently + * clobbering the MMIO region. */ slot0 = memslot2region(vm, 0); - ucall_init(vm, slot0->region.guest_phys_addr + slot0->region.memory_size); + mmio_gpa = slot0->region.guest_phys_addr + slot0->region.memory_size; + ucall_init(vm, mmio_gpa); + + if (vm_check_cap(vm, KVM_CAP_READONLY_MEM)) + vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, + mmio_gpa, KVM_UCALL_MEMSLOT, + vm_adjust_num_guest_pages(vm->mode, 1), + KVM_MEM_READONLY); if (kvm_random_seed != last_kvm_seed) kvm_seed_rng(kvm_random_seed); -- 2.53.0 -- kvm-riscv mailing list kvm-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kvm-riscv From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 86257CCF2C7 for ; 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Sat, 17 Oct 2026 04:03:19 -0700 (PDT) Received: from x1c ([2405:9800:b670:b64b:7c65:ff3e:80ba:b06]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2e97e804dd9sm20559955ad.16.2026.10.17.04.03.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 17 Oct 2026 04:03:18 -0700 (PDT) From: Tharit Tangkijwanichakul To: Paolo Bonzini , Sean Christopherson Cc: Shuah Khan , Marc Zyngier , Oliver Upton , Fuad Tabba , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Anup Patel , Atish Patra , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel-mentees@lists.linux.dev, skhan@linuxfoundation.org, me@brighamcampbell.com, jkoolstra@xs4all.nl, Tharit Tangkijwanichakul Subject: [PATCH 4/5] KVM: selftests: Reserve memslot 1 for the ucall MMIO address Date: Sat, 17 Oct 2026 18:02:12 +0700 Message-ID: <20261017110213.46199-5-tharitt97@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261017110213.46199-1-tharitt97@gmail.com> References: <20261017110213.46199-1-tharitt97@gmail.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261017_040319_795917_220754A1 X-CRM114-Status: GOOD ( 10.34 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Back the ucall MMIO address with a read-only region in slot 1 when KVM_CAP_READONLY_MEM is available. Writes still exit as MMIO, while overlapping memslot creation is rejected. Start test memslots at slot 2, leaving slot 1 reserved by convention even when read-only memory is unsupported. Signed-off-by: Tharit Tangkijwanichakul --- .../testing/selftests/kvm/include/kvm_util.h | 2 +- tools/testing/selftests/kvm/lib/kvm_util.c | 19 +++++++++++++------ 2 files changed, 14 insertions(+), 7 deletions(-) diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h index 759d604d44ce..4dbb2ef332fc 100644 --- a/tools/testing/selftests/kvm/include/kvm_util.h +++ b/tools/testing/selftests/kvm/include/kvm_util.h @@ -30,7 +30,7 @@ #define KVM_DEV_PATH "/dev/kvm" #define KVM_MAX_VCPUS 512 -#define TEST_MEM_SLOT_BASE 1 +#define TEST_MEM_SLOT_BASE 2 #define NSEC_PER_SEC 1000000000L diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c index 9ddc047d5c27..73e28814a226 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -20,6 +20,7 @@ #include #define KVM_UTIL_MIN_PFN 2 +#define KVM_UCALL_MEMSLOT 1 u32 kvm_random_seed; struct kvm_random_state kvm_rng; @@ -492,6 +493,7 @@ struct kvm_vm *__vm_create(struct vm_shape shape, u32 nr_runnable_vcpus, struct userspace_mem_region *slot0; struct kvm_vm *vm; int i, flags; + gpa_t mmio_gpa; kvm_set_files_rlimit(nr_runnable_vcpus); @@ -514,14 +516,19 @@ struct kvm_vm *__vm_create(struct vm_shape shape, u32 nr_runnable_vcpus, kvm_vm_elf_load(vm, program_invocation_name); - /* - * TODO: Add proper defines to protect the library's memslots, and then - * carve out memslot1 for the ucall MMIO address. KVM treats writes to - * read-only memslots as MMIO, and creating a read-only memslot for the - * MMIO region would prevent silently clobbering the MMIO region. + /* KVM treats writes to read-only memslots as MMIO, and creating + * a read-only memslot for the MMIO region would prevent silently + * clobbering the MMIO region. */ slot0 = memslot2region(vm, 0); - ucall_init(vm, slot0->region.guest_phys_addr + slot0->region.memory_size); + mmio_gpa = slot0->region.guest_phys_addr + slot0->region.memory_size; + ucall_init(vm, mmio_gpa); + + if (vm_check_cap(vm, KVM_CAP_READONLY_MEM)) + vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, + mmio_gpa, KVM_UCALL_MEMSLOT, + vm_adjust_num_guest_pages(vm->mode, 1), + KVM_MEM_READONLY); if (kvm_random_seed != last_kvm_seed) kvm_seed_rng(kvm_random_seed); -- 2.53.0 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv