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Date: Tue, 12 Jun 2018 21:06:45 +0800
From: gengdongjiu <gengdongjiu@...wei.com>
To: Marc Zyngier <marc.zyngier@....com>
CC: <rkrcmar@...hat.com>, <corbet@....net>, <christoffer.dall@....com>,
<linux@...linux.org.uk>, <catalin.marinas@....com>,
<will.deacon@....com>, <kvm@...r.kernel.org>,
<linux-doc@...r.kernel.org>, <james.morse@....com>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>, <linux-acpi@...r.kernel.org>
Subject: Re: [PATCH RESEND v4 2/2] arm/arm64: KVM: Add KVM_GET/SET_VCPU_EVENTS
Hi Marc
thanks for the review.
On 2018/6/9 20:40, Marc Zyngier wrote:
> On Fri, 08 Jun 2018 20:48:40 +0100,
> Dongjiu Geng wrote:
>>
>> For the migrating VMs, user space may need to know the exception
>> state. For example, in the machine A, KVM make an SError pending,
>> when migrate to B, KVM also needs to pend an SError.
>>
>> This new IOCTL exports user-invisible states related to SError.
>> Together with appropriate user space changes, user space can get/set
>> the SError exception state to do migrate/snapshot/suspend.
>>
>> Signed-off-by: Dongjiu Geng <gengdongjiu@...wei.com>
>> ---
>> change since v3:
>> 1. Fix the memset() issue in the kvm_arm_vcpu_get_events()
>>
>> change since v2:
>> 1. Add kvm_vcpu_events structure definition for arm platform to avoid the build errors.
>>
>> change since v1:
>> Address Marc's comments, thanks Marc's review
>> 1. serror_has_esr always true when ARM64_HAS_RAS_EXTN is set
>> 2. remove Spurious blank line in kvm_arm_vcpu_set_events()
>> 3. rename pend_guest_serror() to kvm_set_sei_esr()
>> 4. Make kvm_arm_vcpu_get_events() did all the work rather than having this split responsibility.
>> 5. using sizeof(events) instead of sizeof(struct kvm_vcpu_events)
>>
>> this series patch is separated from https://www.spinics.net/lists/kvm/msg168917.html
>> The user space patch is here: https://lists.gnu.org/archive/html/qemu-devel/2018-05/msg06965.html
>>
>> change since V12:
>> 1. change (vcpu->arch.hcr_el2 & HCR_VSE) to !!(vcpu->arch.hcr_el2 & HCR_VSE) in kvm_arm_vcpu_get_events()
>>
>> Change since V11:
>> Address James's comments, thanks James
>> 1. Align the struct of kvm_vcpu_events to 64 bytes
>> 2. Avoid exposing the stale ESR value in the kvm_arm_vcpu_get_events()
>> 3. Change variables 'injected' name to 'serror_pending' in the kvm_arm_vcpu_set_events()
>> 4. Change to sizeof(events) from sizeof(struct kvm_vcpu_events) in kvm_arch_vcpu_ioctl()
>>
>> Change since V10:
>> Address James's comments, thanks James
>> 1. Merge the helper function with the user.
>> 2. Move the ISS_MASK into pend_guest_serror() to clear top bits
>> 3. Make kvm_vcpu_events struct align to 4 bytes
>> 4. Add something check in the kvm_arm_vcpu_set_events()
>> 5. Check kvm_arm_vcpu_get/set_events()'s return value.
>> 6. Initialise kvm_vcpu_events to 0 so that padding transferred to user-space doesn't
>> contain kernel stack.
>> ---
>> Documentation/virtual/kvm/api.txt | 31 ++++++++++++++++++++++++++++---
>> arch/arm/include/asm/kvm_host.h | 6 ++++++
>> arch/arm/include/uapi/asm/kvm.h | 12 ++++++++++++
>> arch/arm/kvm/guest.c | 12 ++++++++++++
>> arch/arm64/include/asm/kvm_emulate.h | 5 +++++
>> arch/arm64/include/asm/kvm_host.h | 7 +++++++
>> arch/arm64/include/uapi/asm/kvm.h | 13 +++++++++++++
>> arch/arm64/kvm/guest.c | 36 ++++++++++++++++++++++++++++++++++++
>> arch/arm64/kvm/inject_fault.c | 6 +++---
>> arch/arm64/kvm/reset.c | 1 +
>> virt/kvm/arm/arm.c | 19 +++++++++++++++++++
>> 11 files changed, 142 insertions(+), 6 deletions(-)
>>
>> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
>> index fdac969..8896737 100644
>> --- a/Documentation/virtual/kvm/api.txt
>> +++ b/Documentation/virtual/kvm/api.txt
>> @@ -835,11 +835,13 @@ struct kvm_clock_data {
>>
>> Capability: KVM_CAP_VCPU_EVENTS
>> Extended by: KVM_CAP_INTR_SHADOW
>> -Architectures: x86
>> +Architectures: x86, arm, arm64
>> Type: vm ioctl
>> Parameters: struct kvm_vcpu_event (out)
>> Returns: 0 on success, -1 on error
>>
>> +X86:
>> +
>> Gets currently pending exceptions, interrupts, and NMIs as well as related
>> states of the vcpu.
>>
>> @@ -881,15 +883,32 @@ Only two fields are defined in the flags field:
>> - KVM_VCPUEVENT_VALID_SMM may be set in the flags field to signal that
>> smi contains a valid state.
>>
>> +ARM, ARM64:
>> +
>> +Gets currently pending SError exceptions as well as related states of the vcpu.
>> +
>> +struct kvm_vcpu_events {
>> + struct {
>> + __u8 serror_pending;
>> + __u8 serror_has_esr;
>> + /* Align it to 8 bytes */
>> + __u8 pad[6];
>> + __u64 serror_esr;
>> + } exception;
>> + __u32 reserved[12];
>> +};
>> +
>> 4.32 KVM_SET_VCPU_EVENTS
>>
>> -Capability: KVM_CAP_VCPU_EVENTS
>> +Capebility: KVM_CAP_VCPU_EVENTS
>> Extended by: KVM_CAP_INTR_SHADOW
>> -Architectures: x86
>> +Architectures: x86, arm, arm64
>> Type: vm ioctl
>> Parameters: struct kvm_vcpu_event (in)
>> Returns: 0 on success, -1 on error
>>
>> +X86:
>> +
>> Set pending exceptions, interrupts, and NMIs as well as related states of the
>> vcpu.
>>
>> @@ -910,6 +929,12 @@ shall be written into the VCPU.
>>
>> KVM_VCPUEVENT_VALID_SMM can only be set if KVM_CAP_X86_SMM is available.
>>
>> +ARM, ARM64:
>> +
>> +Set pending SError exceptions as well as related states of the vcpu.
>> +
>> +See KVM_GET_VCPU_EVENTS for the data structure.
>> +
>>
>> 4.33 KVM_GET_DEBUGREGS
>>
>> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
>> index c7c28c8..39f9901 100644
>> --- a/arch/arm/include/asm/kvm_host.h
>> +++ b/arch/arm/include/asm/kvm_host.h
>> @@ -213,6 +213,12 @@ unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu);
>> int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *indices);
>> int kvm_arm_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
>> int kvm_arm_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
>> +int kvm_arm_vcpu_get_events(struct kvm_vcpu *vcpu,
>> + struct kvm_vcpu_events *events);
>> +
>> +int kvm_arm_vcpu_set_events(struct kvm_vcpu *vcpu,
>> + struct kvm_vcpu_events *events);
>> +
>> unsigned long kvm_call_hyp(void *hypfn, ...);
>> void force_vm_exit(const cpumask_t *mask);
>>
>> diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h
>> index caae484..c3e6975 100644
>> --- a/arch/arm/include/uapi/asm/kvm.h
>> +++ b/arch/arm/include/uapi/asm/kvm.h
>> @@ -124,6 +124,18 @@ struct kvm_sync_regs {
>> struct kvm_arch_memory_slot {
>> };
>>
>> +/* for KVM_GET/SET_VCPU_EVENTS */
>> +struct kvm_vcpu_events {
>> + struct {
>> + __u8 serror_pending;
>> + __u8 serror_has_esr;
>> + /* Align it to 8 bytes */
>> + __u8 pad[6];
>> + __u64 serror_esr;
>> + } exception;
>> + __u32 reserved[12];
>> +};
>> +
>> /* If you need to interpret the index values, here is the key: */
>> #define KVM_REG_ARM_COPROC_MASK 0x000000000FFF0000
>> #define KVM_REG_ARM_COPROC_SHIFT 16
>> diff --git a/arch/arm/kvm/guest.c b/arch/arm/kvm/guest.c
>> index a18f33e..c685f0e 100644
>> --- a/arch/arm/kvm/guest.c
>> +++ b/arch/arm/kvm/guest.c
>> @@ -261,6 +261,18 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
>> return -EINVAL;
>> }
>>
>> +int kvm_arm_vcpu_get_events(struct kvm_vcpu *vcpu,
>> + struct kvm_vcpu_events *events)
>> +{
>> + return -EINVAL;
>> +}
>> +
>> +int kvm_arm_vcpu_set_events(struct kvm_vcpu *vcpu,
>> + struct kvm_vcpu_events *events)
>> +{
>> + return -EINVAL;
>> +}
>> +
>> int __attribute_const__ kvm_target_cpu(void)
>> {
>> switch (read_cpuid_part()) {
>> diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
>> index 1dab3a9..18f61ff 100644
>> --- a/arch/arm64/include/asm/kvm_emulate.h
>> +++ b/arch/arm64/include/asm/kvm_emulate.h
>> @@ -81,6 +81,11 @@ static inline unsigned long *vcpu_hcr(struct kvm_vcpu *vcpu)
>> return (unsigned long *)&vcpu->arch.hcr_el2;
>> }
>>
>> +static inline unsigned long vcpu_get_vsesr(struct kvm_vcpu *vcpu)
>> +{
>> + return vcpu->arch.vsesr_el2;
>> +}
>> +
>> static inline void vcpu_set_vsesr(struct kvm_vcpu *vcpu, u64 vsesr)
>> {
>> vcpu->arch.vsesr_el2 = vsesr;
>> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
>> index 469de8a..357304a 100644
>> --- a/arch/arm64/include/asm/kvm_host.h
>> +++ b/arch/arm64/include/asm/kvm_host.h
>> @@ -335,6 +335,11 @@ unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu);
>> int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *indices);
>> int kvm_arm_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
>> int kvm_arm_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
>> +int kvm_arm_vcpu_get_events(struct kvm_vcpu *vcpu,
>> + struct kvm_vcpu_events *events);
>> +
>> +int kvm_arm_vcpu_set_events(struct kvm_vcpu *vcpu,
>> + struct kvm_vcpu_events *events);
>>
>> #define KVM_ARCH_WANT_MMU_NOTIFIER
>> int kvm_unmap_hva(struct kvm *kvm, unsigned long hva);
>> @@ -363,6 +368,8 @@ void handle_exit_early(struct kvm_vcpu *vcpu, struct kvm_run *run,
>> int kvm_perf_init(void);
>> int kvm_perf_teardown(void);
>>
>> +void kvm_set_sei_esr(struct kvm_vcpu *vcpu, u64 syndrome);
>> +
>> struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
>>
>> void __kvm_set_tpidr_el2(u64 tpidr_el2);
>> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
>> index 04b3256..df4faee 100644
>> --- a/arch/arm64/include/uapi/asm/kvm.h
>> +++ b/arch/arm64/include/uapi/asm/kvm.h
>> @@ -39,6 +39,7 @@
>> #define __KVM_HAVE_GUEST_DEBUG
>> #define __KVM_HAVE_IRQ_LINE
>> #define __KVM_HAVE_READONLY_MEM
>> +#define __KVM_HAVE_VCPU_EVENTS
>>
>> #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
>>
>> @@ -153,6 +154,18 @@ struct kvm_sync_regs {
>> struct kvm_arch_memory_slot {
>> };
>>
>> +/* for KVM_GET/SET_VCPU_EVENTS */
>> +struct kvm_vcpu_events {
>> + struct {
>> + __u8 serror_pending;
>> + __u8 serror_has_esr;
>> + /* Align it to 8 bytes */
>> + __u8 pad[6];
>> + __u64 serror_esr;
>> + } exception;
>> + __u32 reserved[12];
>> +};
>> +
>> /* If you need to interpret the index values, here is the key: */
>> #define KVM_REG_ARM_COPROC_MASK 0x000000000FFF0000
>> #define KVM_REG_ARM_COPROC_SHIFT 16
>> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
>> index 56a0260..4426915 100644
>> --- a/arch/arm64/kvm/guest.c
>> +++ b/arch/arm64/kvm/guest.c
>> @@ -289,6 +289,42 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
>> return -EINVAL;
>> }
>>
>> +int kvm_arm_vcpu_get_events(struct kvm_vcpu *vcpu,
>> + struct kvm_vcpu_events *events)
>> +{
>> + memset(events, 0, sizeof(*events));
>> +
>> + events->exception.serror_pending = !!(vcpu->arch.hcr_el2 & HCR_VSE);
>> + events->exception.serror_has_esr =
>> + cpus_have_const_cap(ARM64_HAS_RAS_EXTN);
>> +
>> + if (events->exception.serror_pending &&
>> + events->exception.serror_has_esr)
>> + events->exception.serror_esr = vcpu_get_vsesr(vcpu);
>> + else
>> + events->exception.serror_esr = 0;
>
> Other than the alignment issues that Christoffer already commented on,
> you can perfectly remove the "else" clause altogether (we've just
> zeroed the whole structure).
yes, you are right. it should be moved, thanks for the pointing out.
>
>> +
>> + return 0;
>> +}
>> +
>> +int kvm_arm_vcpu_set_events(struct kvm_vcpu *vcpu,
>> + struct kvm_vcpu_events *events)
>> +{
>> + bool serror_pending = events->exception.serror_pending;
>> + bool has_esr = events->exception.serror_has_esr;
>> +
>> + if (serror_pending && has_esr) {
>> + if (!cpus_have_const_cap(ARM64_HAS_RAS_EXTN))
>> + return -EINVAL;
>> +
>> + kvm_set_sei_esr(vcpu, events->exception.serror_esr);
>> + } else if (serror_pending) {
>> + kvm_inject_vabt(vcpu);
>> + }
>> +
>> + return 0;
>
> There was an earlier request to check that all the padding is set to
> zero. I still think this makes sense.
previously I think it may be not needed to check that all the padding is set to
zero. so not added it. but now I consider it again, it should be make sense to check that.
so I will added them. thanks for the mention again.
>
> Thanks,
>
> M.
>
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