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Re: [Qemu-devel] [PATCH 09/10] s390x/mmu: Use ioctl for reading and writ
From: |
Christian Borntraeger |
Subject: |
Re: [Qemu-devel] [PATCH 09/10] s390x/mmu: Use ioctl for reading and writing from/to guest memory |
Date: |
Tue, 21 Apr 2015 21:48:02 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 |
Am 21.04.2015 um 21:36 schrieb Alexander Graf:
> 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 <address@hidden>
>>>>>
>>>>> 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 <address@hidden>
>>>>> Signed-off-by: Cornelia Huck <address@hidden>
>>>> Acked-by: Christian Borntraeger <address@hidden>
>>>>
>>>>> ---
>>>>> 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?
>
We could move the error_printf into kvm_s390_mem_op.
Well Conny has to do it as Thomas has left IBM.
- Re: [Qemu-devel] [PATCH 05/10] s390x/ipl: sort into categories, (continued)
[Qemu-devel] [PATCH 07/10] linux-headers: update, Cornelia Huck, 2015/04/09
[Qemu-devel] [PATCH 10/10] s390x/kvm: Support access register mode for KVM_S390_MEM_OP ioctl, Cornelia Huck, 2015/04/09