From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33018) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yke08-0008So-6O for qemu-devel@nongnu.org; Tue, 21 Apr 2015 15:38:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Yke02-0003UM-Vn for qemu-devel@nongnu.org; Tue, 21 Apr 2015 15:38:32 -0400 Received: from cantor2.suse.de ([195.135.220.15]:59205 helo=mx2.suse.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yke02-0003To-MK for qemu-devel@nongnu.org; Tue, 21 Apr 2015 15:38:26 -0400 Message-ID: <5536A6C8.5010504@suse.de> Date: Tue, 21 Apr 2015 21:36:40 +0200 From: Alexander Graf MIME-Version: 1.0 References: <1428569498-27393-1-git-send-email-cornelia.huck@de.ibm.com> <1428569498-27393-10-git-send-email-cornelia.huck@de.ibm.com> <55351366.9000600@de.ibm.com> <5536A11E.5020609@suse.de> <5536A65E.5090204@de.ibm.com> In-Reply-To: <5536A65E.5090204@de.ibm.com> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 09/10] s390x/mmu: Use ioctl for reading and writing from/to guest memory List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Christian Borntraeger , Cornelia Huck , qemu-devel@nongnu.org Cc: jfrei@linux.vnet.ibm.com, Thomas Huth On 04/21/2015 09:34 PM, Christian Borntraeger wrote: > Am 21.04.2015 um 21:12 schrieb Alexander Graf: >> On 04/20/2015 04:55 PM, Christian Borntraeger wrote: >>> Am 09.04.2015 um 10:51 schrieb Cornelia Huck: >>>> From: Thomas Huth >>>> >>>> Add code to make use of the new ioctl for reading from / writing to >>>> virtual guest memory. By using the ioctl, the memory accesses are now >>>> protected with the so-called ipte-lock in the kernel. >>>> >>>> Signed-off-by: Thomas Huth >>>> Signed-off-by: Cornelia Huck >>> Acked-by: Christian Borntraeger >>> >>>> --- >>>> target-s390x/cpu.h | 7 +++++++ >>>> target-s390x/kvm.c | 35 +++++++++++++++++++++++++++++++++++ >>>> target-s390x/mmu_helper.c | 9 +++++++++ >>>> 3 files changed, 51 insertions(+) >>>> >>>> diff --git a/target-s390x/cpu.h b/target-s390x/cpu.h >>>> index 79bc80b..9c42743 100644 >>>> --- a/target-s390x/cpu.h >>>> +++ b/target-s390x/cpu.h >>>> @@ -401,6 +401,8 @@ void kvm_s390_vcpu_interrupt(S390CPU *cpu, struct kvm_s390_irq *irq); >>>> void kvm_s390_floating_interrupt(struct kvm_s390_irq *irq); >>>> int kvm_s390_inject_flic(struct kvm_s390_irq *irq); >>>> void kvm_s390_access_exception(S390CPU *cpu, uint16_t code, uint64_t te_code); >>>> +int kvm_s390_mem_op(S390CPU *cpu, vaddr addr, void *hostbuf, int len, >>>> + bool is_write); >>>> int kvm_s390_get_clock(uint8_t *tod_high, uint64_t *tod_clock); >>>> int kvm_s390_set_clock(uint8_t *tod_high, uint64_t *tod_clock); >>>> #else >>>> @@ -418,6 +420,11 @@ static inline int kvm_s390_set_clock(uint8_t *tod_high, uint64_t *tod_low) >>>> { >>>> return -ENOSYS; >>>> } >>>> +static inline int kvm_s390_mem_op(S390CPU *cpu, vaddr addr, void *hostbuf, >>>> + int len, bool is_write) >>>> +{ >>>> + return -ENOSYS; >>>> +} >>>> static inline void kvm_s390_access_exception(S390CPU *cpu, uint16_t code, >>>> uint64_t te_code) >>>> { >>>> diff --git a/target-s390x/kvm.c b/target-s390x/kvm.c >>>> index 619684b..e2ae2b3 100644 >>>> --- a/target-s390x/kvm.c >>>> +++ b/target-s390x/kvm.c >>>> @@ -123,6 +123,7 @@ const KVMCapabilityInfo kvm_arch_required_capabilities[] = { >>>> >>>> static int cap_sync_regs; >>>> static int cap_async_pf; >>>> +static int cap_mem_op; >>>> >>>> static void *legacy_s390_alloc(size_t size, uint64_t *align); >>>> >>>> @@ -247,6 +248,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s) >>>> { >>>> cap_sync_regs = kvm_check_extension(s, KVM_CAP_SYNC_REGS); >>>> cap_async_pf = kvm_check_extension(s, KVM_CAP_ASYNC_PF); >>>> + cap_mem_op = kvm_check_extension(s, KVM_CAP_S390_MEM_OP); >>>> >>>> kvm_s390_enable_cmma(s); >>>> >>>> @@ -550,6 +552,39 @@ int kvm_s390_set_clock(uint8_t *tod_high, uint64_t *tod_low) >>>> return kvm_vm_ioctl(kvm_state, KVM_SET_DEVICE_ATTR, &attr); >>>> } >>>> >>>> +/** >>>> + * kvm_s390_mem_op: >>>> + * @addr: the logical start address in guest memory >>>> + * @hostbuf: buffer in host memory. NULL = do only checks w/o copying >>>> + * @len: length that should be transfered >>>> + * @is_write: true = write, false = read >>>> + * Returns: 0 on success, non-zero if an exception or error occured >>>> + * >>>> + * Use KVM ioctl to read/write from/to guest memory. An access exception >>>> + * is injected into the vCPU in case of translation errors. >>>> + */ >>>> +int kvm_s390_mem_op(S390CPU *cpu, vaddr addr, void *hostbuf, int len, >>>> + bool is_write) >>>> +{ >>>> + struct kvm_s390_mem_op mem_op = { >>>> + .gaddr = addr, >>>> + .flags = KVM_S390_MEMOP_F_INJECT_EXCEPTION, >>>> + .size = len, >>>> + .op = is_write ? KVM_S390_MEMOP_LOGICAL_WRITE >>>> + : KVM_S390_MEMOP_LOGICAL_READ, >>>> + .buf = (uint64_t)hostbuf, >>>> + }; >>>> + >>>> + if (!cap_mem_op) { >>>> + return -ENOSYS; >>>> + } >>>> + if (!hostbuf) { >>>> + mem_op.flags |= KVM_S390_MEMOP_F_CHECK_ONLY; >>>> + } >>>> + >>>> + return kvm_vcpu_ioctl(CPU(cpu), KVM_S390_MEM_OP, &mem_op); >>>> +} >>>> + >>>> /* >>>> * Legacy layout for s390: >>>> * Older S390 KVM requires the topmost vma of the RAM to be >>>> diff --git a/target-s390x/mmu_helper.c b/target-s390x/mmu_helper.c >>>> index 9b88498..1e7412c 100644 >>>> --- a/target-s390x/mmu_helper.c >>>> +++ b/target-s390x/mmu_helper.c >>>> @@ -450,6 +450,15 @@ int s390_cpu_virt_mem_rw(S390CPU *cpu, vaddr laddr, void *hostbuf, >>>> target_ulong *pages; >>>> int ret; >>>> >>>> + if (kvm_enabled()) { >>>> + ret = kvm_s390_mem_op(cpu, laddr, hostbuf, len, is_write); >>>> + if (ret >= 0) { >>>> + return ret; >>>> + } else if (ret != -ENOSYS) { >>>> + error_printf("kvm_s390_mem_op() failed: %s\n", strerror(-ret)); >> Won't this spill the logs like crazy when running new qemu on old kernels? > kvm_s390_mem_op will return -ENOSYS if cap_mem_op is not set. Oh, I see the logic now. Can you think of any way to make it more obvious to a reader what's going on? Alex