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Message-ID: <8b92fb5b-5138-0695-fb90-6c36b8dfad00@linux.alibaba.com>
Date: Thu, 16 Apr 2020 16:45:33 +0800
From: Tianjia Zhang <tianjia.zhang@...ux.alibaba.com>
To: Marc Zyngier <maz@...nel.org>,
Vitaly Kuznetsov <vkuznets@...hat.com>
Cc: kvm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
kvmarm@...ts.cs.columbia.edu, linux-mips@...r.kernel.org,
kvm-ppc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
pbonzini@...hat.com, tsbogend@...ha.franken.de, paulus@...abs.org,
mpe@...erman.id.au, benh@...nel.crashing.org,
borntraeger@...ibm.com, frankja@...ux.ibm.com, david@...hat.com,
cohuck@...hat.com, heiko.carstens@...ibm.com, gor@...ux.ibm.com,
sean.j.christopherson@...el.com, wanpengli@...cent.com,
jmattson@...gle.com, joro@...tes.org, tglx@...utronix.de,
mingo@...hat.com, bp@...en8.de, x86@...nel.org, hpa@...or.com,
james.morse@....com, julien.thierry.kdev@...il.com,
suzuki.poulose@....com, christoffer.dall@....com,
peterx@...hat.com, thuth@...hat.com
Subject: Re: [PATCH v2] KVM: Optimize kvm_arch_vcpu_ioctl_run function
On 2020/4/16 16:28, Marc Zyngier wrote:
> On 2020-04-16 08:03, Vitaly Kuznetsov wrote:
>> Tianjia Zhang <tianjia.zhang@...ux.alibaba.com> writes:
>>
>>> In earlier versions of kvm, 'kvm_run' is an independent structure
>>> and is not included in the vcpu structure. At present, 'kvm_run'
>>> is already included in the vcpu structure, so the parameter
>>> 'kvm_run' is redundant.
>>>
>>> This patch simplify the function definition, removes the extra
>>> 'kvm_run' parameter, and extract it from the 'kvm_vcpu' structure
>>> if necessary.
>>>
>>> Signed-off-by: Tianjia Zhang <tianjia.zhang@...ux.alibaba.com>
>>> ---
>>>
>>> v2 change:
>>> remove 'kvm_run' parameter and extract it from 'kvm_vcpu'
>>>
>>> arch/mips/kvm/mips.c | 3 ++-
>>> arch/powerpc/kvm/powerpc.c | 3 ++-
>>> arch/s390/kvm/kvm-s390.c | 3 ++-
>>> arch/x86/kvm/x86.c | 11 ++++++-----
>>> include/linux/kvm_host.h | 2 +-
>>> virt/kvm/arm/arm.c | 6 +++---
>>> virt/kvm/kvm_main.c | 2 +-
>>> 7 files changed, 17 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
>>> index 8f05dd0a0f4e..ec24adf4857e 100644
>>> --- a/arch/mips/kvm/mips.c
>>> +++ b/arch/mips/kvm/mips.c
>>> @@ -439,8 +439,9 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct
>>> kvm_vcpu *vcpu,
>>> return -ENOIOCTLCMD;
>>> }
>>>
>>> -int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
>>> +int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
>>> {
>>> + struct kvm_run *run = vcpu->run;
>>> int r = -EINTR;
>>>
>>> vcpu_load(vcpu);
>>> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
>>> index e15166b0a16d..7e24691e138a 100644
>>> --- a/arch/powerpc/kvm/powerpc.c
>>> +++ b/arch/powerpc/kvm/powerpc.c
>>> @@ -1764,8 +1764,9 @@ int kvm_vcpu_ioctl_set_one_reg(struct kvm_vcpu
>>> *vcpu, struct kvm_one_reg *reg)
>>> return r;
>>> }
>>>
>>> -int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
>>> +int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
>>> {
>>> + struct kvm_run *run = vcpu->run;
>>> int r;
>>>
>>> vcpu_load(vcpu);
>>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>>> index 19a81024fe16..443af3ead739 100644
>>> --- a/arch/s390/kvm/kvm-s390.c
>>> +++ b/arch/s390/kvm/kvm-s390.c
>>> @@ -4333,8 +4333,9 @@ static void store_regs(struct kvm_vcpu *vcpu,
>>> struct kvm_run *kvm_run)
>>> store_regs_fmt2(vcpu, kvm_run);
>>> }
>>>
>>> -int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run
>>> *kvm_run)
>>> +int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
>>> {
>>> + struct kvm_run *kvm_run = vcpu->run;
>>> int rc;
>>>
>>> if (kvm_run->immediate_exit)
>>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>>> index 3bf2ecafd027..a0338e86c90f 100644
>>> --- a/arch/x86/kvm/x86.c
>>> +++ b/arch/x86/kvm/x86.c
>>> @@ -8707,8 +8707,9 @@ static void kvm_put_guest_fpu(struct kvm_vcpu
>>> *vcpu)
>>> trace_kvm_fpu(0);
>>> }
>>>
>>> -int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run
>>> *kvm_run)
>>> +int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
>>> {
>>> + struct kvm_run *kvm_run = vcpu->run;
>>> int r;
>>>
>>> vcpu_load(vcpu);
>>> @@ -8726,18 +8727,18 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu
>>> *vcpu, struct kvm_run *kvm_run)
>>> r = -EAGAIN;
>>> if (signal_pending(current)) {
>>> r = -EINTR;
>>> - vcpu->run->exit_reason = KVM_EXIT_INTR;
>>> + kvm_run->exit_reason = KVM_EXIT_INTR;
>>> ++vcpu->stat.signal_exits;
>>> }
>>> goto out;
>>> }
>>>
>>> - if (vcpu->run->kvm_valid_regs & ~KVM_SYNC_X86_VALID_FIELDS) {
>>> + if (kvm_run->kvm_valid_regs & ~KVM_SYNC_X86_VALID_FIELDS) {
>>> r = -EINVAL;
>>> goto out;
>>> }
>>>
>>> - if (vcpu->run->kvm_dirty_regs) {
>>> + if (kvm_run->kvm_dirty_regs) {
>>> r = sync_regs(vcpu);
>>> if (r != 0)
>>> goto out;
>>> @@ -8767,7 +8768,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu
>>> *vcpu, struct kvm_run *kvm_run)
>>>
>>> out:
>>> kvm_put_guest_fpu(vcpu);
>>> - if (vcpu->run->kvm_valid_regs)
>>> + if (kvm_run->kvm_valid_regs)
>>> store_regs(vcpu);
>>> post_kvm_run_save(vcpu);
>>> kvm_sigset_deactivate(vcpu);
>>> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
>>> index 6d58beb65454..1e17ef719595 100644
>>> --- a/include/linux/kvm_host.h
>>> +++ b/include/linux/kvm_host.h
>>> @@ -866,7 +866,7 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct
>>> kvm_vcpu *vcpu,
>>> struct kvm_mp_state *mp_state);
>>> int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
>>> struct kvm_guest_debug *dbg);
>>> -int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run
>>> *kvm_run);
>>> +int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu);
>>>
>>> int kvm_arch_init(void *opaque);
>>> void kvm_arch_exit(void);
>>> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
>>> index 48d0ec44ad77..f5390ac2165b 100644
>>> --- a/virt/kvm/arm/arm.c
>>> +++ b/virt/kvm/arm/arm.c
>>> @@ -639,7 +639,6 @@ static void check_vcpu_requests(struct kvm_vcpu
>>> *vcpu)
>>> /**
>>> * kvm_arch_vcpu_ioctl_run - the main VCPU run function to execute
>>> guest code
>>> * @vcpu: The VCPU pointer
>>> - * @run: The kvm_run structure pointer used for userspace state
>>> exchange
>>> *
>>> * This function is called through the VCPU_RUN ioctl called from
>>> user space. It
>>> * will execute VM code in a loop until the time slice for the
>>> process is used
>>> @@ -647,8 +646,9 @@ static void check_vcpu_requests(struct kvm_vcpu
>>> *vcpu)
>>> * return with return value 0 and with the kvm_run structure filled
>>> in with the
>>> * required data for the requested emulation.
>>> */
>>> -int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
>>> +int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
>>> {
>>> + struct kvm_run *run = vcpu->run;
>>> int ret;
>>>
>>> if (unlikely(!kvm_vcpu_initialized(vcpu)))
>>> @@ -659,7 +659,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu
>>> *vcpu, struct kvm_run *run)
>>> return ret;
>>>
>>> if (run->exit_reason == KVM_EXIT_MMIO) {
>>> - ret = kvm_handle_mmio_return(vcpu, vcpu->run);
>>> + ret = kvm_handle_mmio_return(vcpu, run);
>>
>> I don't know much about ARM but this also seems redundant,
>> kvm_handle_mmio_return() is also able to extruct 'struct kvm_run' from'
>> 'struct kvm_vcpu'. This likely deserves it's own patch though.
>
> Something like this (untested):
>
> diff --git a/arch/arm64/include/asm/kvm_host.h
> b/arch/arm64/include/asm/kvm_host.h
> index 32c8a675e5a4..82978995bdd6 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -490,7 +490,7 @@ void handle_exit_early(struct kvm_vcpu *vcpu, struct
> kvm_run *run,
> void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data);
> unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len);
>
> -int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run);
> +int kvm_handle_mmio_return(struct kvm_vcpu *vcpu);
> int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
> phys_addr_t fault_ipa);
>
> diff --git a/virt/kvm/arm/mmio.c b/virt/kvm/arm/mmio.c
> index 4e0366759726..3b2c822b4859 100644
> --- a/virt/kvm/arm/mmio.c
> +++ b/virt/kvm/arm/mmio.c
> @@ -77,9 +77,8 @@ unsigned long kvm_mmio_read_buf(const void *buf,
> unsigned int len)
> * or in-kernel IO emulation
> *
> * @vcpu: The VCPU pointer
> - * @run: The VCPU run struct containing the mmio data
> */
> -int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
> +int kvm_handle_mmio_return(struct kvm_vcpu *vcpu)
> {
> unsigned long data;
> unsigned int len;
> @@ -93,7 +92,7 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu,
> struct kvm_run *run)
>
> if (!kvm_vcpu_dabt_iswrite(vcpu)) {
> len = kvm_vcpu_dabt_get_as(vcpu);
> - data = kvm_mmio_read_buf(run->mmio.data, len);
> + data = kvm_mmio_read_buf(vcpu->run->mmio.data, len);
>
> if (kvm_vcpu_dabt_issext(vcpu) &&
> len < sizeof(unsigned long)) {
> @@ -104,7 +103,8 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu,
> struct kvm_run *run)
> if (!kvm_vcpu_dabt_issf(vcpu))
> data = data & 0xffffffff;
>
> - trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
> + trace_kvm_mmio(KVM_TRACE_MMIO_READ, len,
> + vcpu->run->mmio.phys_addr,
> &data);
> data = vcpu_data_host_to_guest(vcpu, data, len);
> vcpu_set_reg(vcpu, kvm_vcpu_dabt_get_rd(vcpu), data);
>
> Overall, there is a large set of cleanups to be done when both the vcpu
> and the run
> structures are passed as parameters at the same time. Just grepping the
> tree for
> kvm_run is pretty instructive.
>
> M.
Sorry, it's my mistake, I only compiled the x86 platform, I will submit
patch again.
Thanks,
Tianjia
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