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[2003:cb:c713:7800:820d:e9f:8ce:52bd]) by smtp.gmail.com with UTF8SMTPSA id 5b1f17b1804b1-4366120088esm82859165e9.13.2024.12.21.11.22.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 21 Dec 2024 11:22:33 -0800 (PST) From: David Hildenbrand To: qemu-devel@nongnu.org Cc: Halil Pasic , Christian Borntraeger , Eric Farman , Thomas Huth , Richard Henderson , "Michael S . Tsirkin" , David Hildenbrand Subject: [PULL v2 08/15] s390x/s390-hypercall: introduce DIAG500 STORAGE_LIMIT Date: Sat, 21 Dec 2024 20:22:02 +0100 Message-ID: <20241221192209.3979595-9-david@redhat.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241221192209.3979595-1-david@redhat.com> References: <20241221192209.3979595-1-david@redhat.com> MIME-Version: 1.0 Received-SPF: pass client-ip=170.10.133.124; envelope-from=dhildenb@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -32 X-Spam_score: -3.3 X-Spam_bar: --- X-Spam_report: (-3.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-1.177, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org A guest OS that supports memory hotplug / memory devices must during boot be aware of the maximum possible physical memory address that it might have to handle at a later stage during its runtime. For example, the maximum possible memory address might be required to prepare the kernel virtual address space accordingly (e.g., select page table hierarchy depth). On s390x there is currently no such mechanism that is compatible with paravirtualized memory devices, because the whole SCLP interface was designed around the idea of "storage increments" and "standby memory". Paravirtualized memory devices we want to support, such as virtio-mem, have no intersection with any of that, but could co-exist with them in the future if ever needed. In particular, a guest OS must never detect and use device memory without the help of a proper device driver. Device memory must not be exposed in any firmware-provided memory map (SCLP or diag260 on s390x). For this reason, these memory devices will be places in memory *above* the "maximum storage increment" exposed via SCLP. Let's provide a new diag500 subcode to query the memory limit determined in s390_memory_init(). Message-ID: <20241219144115.2820241-8-david@redhat.com> Acked-by: Michael S. Tsirkin Reviewed-by: Thomas Huth Signed-off-by: David Hildenbrand --- hw/s390x/s390-hypercall.c | 12 +++++++++++- hw/s390x/s390-hypercall.h | 1 + 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/hw/s390x/s390-hypercall.c b/hw/s390x/s390-hypercall.c index f816c2b1ef..ac1b08b2cd 100644 --- a/hw/s390x/s390-hypercall.c +++ b/hw/s390x/s390-hypercall.c @@ -11,7 +11,7 @@ #include "qemu/osdep.h" #include "cpu.h" -#include "hw/boards.h" +#include "hw/s390x/s390-virtio-ccw.h" #include "hw/s390x/s390-hypercall.h" #include "hw/s390x/ioinst.h" #include "hw/s390x/css.h" @@ -57,6 +57,13 @@ static int handle_virtio_ccw_notify(uint64_t subch_id, uint64_t data) return 0; } +static uint64_t handle_storage_limit(void) +{ + S390CcwMachineState *s390ms = S390_CCW_MACHINE(qdev_get_machine()); + + return s390_get_memory_limit(s390ms) - 1; +} + void handle_diag_500(S390CPU *cpu, uintptr_t ra) { CPUS390XState *env = &cpu->env; @@ -69,6 +76,9 @@ void handle_diag_500(S390CPU *cpu, uintptr_t ra) case DIAG500_VIRTIO_CCW_NOTIFY: env->regs[2] = handle_virtio_ccw_notify(env->regs[2], env->regs[3]); break; + case DIAG500_STORAGE_LIMIT: + env->regs[2] = handle_storage_limit(); + break; default: s390_program_interrupt(env, PGM_SPECIFICATION, ra); } diff --git a/hw/s390x/s390-hypercall.h b/hw/s390x/s390-hypercall.h index 2fa81dbfdd..4f07209128 100644 --- a/hw/s390x/s390-hypercall.h +++ b/hw/s390x/s390-hypercall.h @@ -18,6 +18,7 @@ #define DIAG500_VIRTIO_RESET 1 /* legacy */ #define DIAG500_VIRTIO_SET_STATUS 2 /* legacy */ #define DIAG500_VIRTIO_CCW_NOTIFY 3 /* KVM_S390_VIRTIO_CCW_NOTIFY */ +#define DIAG500_STORAGE_LIMIT 4 void handle_diag_500(S390CPU *cpu, uintptr_t ra);