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    SubjectRe: [PATCH RESEND v4 2/2] arm/arm64: KVM: Add KVM_GET/SET_VCPU_EVENTS
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    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@huawei.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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