On Wed, Feb 16, 2022 at 04:59:10PM +0000, Marc Zyngier wrote:
> Hi Sebastian,
>
> Thanks for looking into this. A few comments below.
>
Hello Marc,
Thanks for taking the time to review my patch.
> On 2022-02-16 16:16, Sebastian Ene wrote:
> > This patch add support for stolen time by sharing a memory region
> > with the guest which will be used by the hypervisor to store the stolen
> > time information. The exact format of the structure stored by the
> > hypervisor is described in the ARM DEN0057A document.
> >
> > Signed-off-by: Sebastian Ene <sebastianene@xxxxxxxxxx>
> > ---
> > Makefile | 3 +-
> > arm/aarch64/arm-cpu.c | 2 +
> > arm/aarch64/include/kvm/pvtime.h | 6 +++
> > arm/aarch64/pvtime.c | 83 +++++++++++++++++++++++++++++++
> > arm/include/arm-common/kvm-arch.h | 6 +++
> > arm/kvm-cpu.c | 14 +++---
> > 6 files changed, 106 insertions(+), 8 deletions(-)
> > create mode 100644 arm/aarch64/include/kvm/pvtime.h
> > create mode 100644 arm/aarch64/pvtime.c
> >
> > diff --git a/Makefile b/Makefile
> > index f251147..282ae99 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -182,6 +182,7 @@ ifeq ($(ARCH), arm64)
> > OBJS += arm/aarch64/arm-cpu.o
> > OBJS += arm/aarch64/kvm-cpu.o
> > OBJS += arm/aarch64/kvm.o
> > + OBJS += arm/aarch64/pvtime.o
> > ARCH_INCLUDE := $(HDRS_ARM_COMMON)
> > ARCH_INCLUDE += -Iarm/aarch64/include
> >
> > @@ -582,4 +583,4 @@ ifneq ($(MAKECMDGOALS),clean)
> >
> > KVMTOOLS-VERSION-FILE:
> > @$(SHELL_PATH) util/KVMTOOLS-VERSION-GEN $(OUTPUT)
> > -endif
> > \ No newline at end of file
> > +endif
>
> Spurious change?
>
Right, ACK I will revert this change.
> > diff --git a/arm/aarch64/arm-cpu.c b/arm/aarch64/arm-cpu.c
> > index d7572b7..80bf83a 100644
> > --- a/arm/aarch64/arm-cpu.c
> > +++ b/arm/aarch64/arm-cpu.c
> > @@ -2,6 +2,7 @@
> > #include "kvm/kvm.h"
> > #include "kvm/kvm-cpu.h"
> > #include "kvm/util.h"
> > +#include "kvm/pvtime.h"
> >
> > #include "arm-common/gic.h"
> > #include "arm-common/timer.h"
> > @@ -22,6 +23,7 @@ static void generate_fdt_nodes(void *fdt, struct kvm
> > *kvm)
> > static int arm_cpu__vcpu_init(struct kvm_cpu *vcpu)
> > {
> > vcpu->generate_fdt_nodes = generate_fdt_nodes;
> > + pvtime__setup_vcpu(vcpu);
> > return 0;
> > }
> >
> > diff --git a/arm/aarch64/include/kvm/pvtime.h
> > b/arm/aarch64/include/kvm/pvtime.h
> > new file mode 100644
> > index 0000000..c31f019
> > --- /dev/null
> > +++ b/arm/aarch64/include/kvm/pvtime.h
> > @@ -0,0 +1,6 @@
> > +#ifndef KVM__PVTIME_H
> > +#define KVM__PVTIME_H
> > +
> > +void pvtime__setup_vcpu(struct kvm_cpu *vcpu);
> > +
> > +#endif /* KVM__PVTIME_H */
>
> How about sticking this in kvm-cpu-arch.h instead? A whole new include file
> for just a prototype isn't totally warranted.
>
I think that's a good ideea, I will do this.
> > diff --git a/arm/aarch64/pvtime.c b/arm/aarch64/pvtime.c
> > new file mode 100644
> > index 0000000..eb92388
> > --- /dev/null
> > +++ b/arm/aarch64/pvtime.c
> > @@ -0,0 +1,83 @@
> > +#include "kvm/kvm.h"
> > +#include "kvm/kvm-cpu.h"
> > +#include "kvm/util.h"
> > +#include "kvm/pvtime.h"
> > +
> > +#include <linux/byteorder.h>
> > +#include <linux/types.h>
> > +
> > +struct pvtime_data_priv {
> > + bool is_supported;
> > + char *usr_mem;
> > +};
> > +
> > +static struct pvtime_data_priv pvtime_data = {
> > + .is_supported = true,
> > + .usr_mem = NULL
> > +};
> > +
> > +static int pvtime__aloc_region(struct kvm *kvm)
>
> s/aloc/alloc/ ?
>
I will fix the typo.
> > +{
> > + char *mem;
> > + int ret = 0;
> > +
> > + mem = mmap(NULL, AARCH64_PVTIME_IPA_MAX_SIZE, PROT_RW,
> > + MAP_ANON_NORESERVE, -1, 0);
> > + if (mem == MAP_FAILED)
> > + return -ENOMEM;
> > +
> > + ret = kvm__register_dev_mem(kvm, AARCH64_PVTIME_IPA_START,
> > + AARCH64_PVTIME_IPA_MAX_SIZE, mem);
> > + if (ret) {
> > + munmap(mem, AARCH64_PVTIME_IPA_MAX_SIZE);
> > + return ret;
> > + }
> > +
> > + pvtime_data.usr_mem = mem;
> > + return ret;
> > +}
> > +
> > +static int pvtime__teardown_region(struct kvm *kvm)
> > +{
> > + kvm__destroy_mem(kvm, AARCH64_PVTIME_IPA_START,
> > + AARCH64_PVTIME_IPA_MAX_SIZE, pvtime_data.usr_mem);
> > + munmap(pvtime_data.usr_mem, AARCH64_PVTIME_IPA_MAX_SIZE);
> > + pvtime_data.usr_mem = NULL;
> > + return 0;
> > +}
> > +
> > +void pvtime__setup_vcpu(struct kvm_cpu *vcpu)
> > +{
> > + int ret;
> > + u64 pvtime_guest_addr = AARCH64_PVTIME_IPA_START + vcpu->cpu_id *
> > + AARCH64_PVTIME_SIZE;
> > + struct kvm_device_attr pvtime_attr = (struct kvm_device_attr) {
> > + .group = KVM_ARM_VCPU_PVTIME_CTRL,
> > + .addr = KVM_ARM_VCPU_PVTIME_IPA
> > + };
> > +
> > + if (!pvtime_data.is_supported)
> > + return;
> > +
> > + if (!pvtime_data.usr_mem) {
> > + ret = pvtime__aloc_region(vcpu->kvm);
> > + if (ret)
> > + goto out_err_alloc;
> > + }
> > +
> > + ret = ioctl(vcpu->vcpu_fd, KVM_HAS_DEVICE_ATTR, &pvtime_attr);
> > + if (ret)
> > + goto out_err_attr;
>
> You should check for the stolen time capability before allocating and
> mapping
> the memory.
>
Good catch ! I will do this, thanks.
> > +
> > + pvtime_attr.addr = (u64)&pvtime_guest_addr;
> > + ret = ioctl(vcpu->vcpu_fd, KVM_SET_DEVICE_ATTR, &pvtime_attr);
> > + if (!ret)
> > + return;
> > +
> > +out_err_attr:
> > + pvtime__teardown_region(vcpu->kvm);
> > +out_err_alloc:
> > + pvtime_data.is_supported = false;
> > +}
> > +
> > +dev_exit(pvtime__teardown_region);
> > diff --git a/arm/include/arm-common/kvm-arch.h
> > b/arm/include/arm-common/kvm-arch.h
> > index c645ac0..7b683d6 100644
> > --- a/arm/include/arm-common/kvm-arch.h
> > +++ b/arm/include/arm-common/kvm-arch.h
> > @@ -54,6 +54,12 @@
> > #define ARM_PCI_MMIO_SIZE (ARM_MEMORY_AREA - \
> > (ARM_AXI_AREA + ARM_PCI_CFG_SIZE))
> >
> > +#define AARCH64_PVTIME_IPA_MAX_SIZE (0x10000)
>
> SZ_64K?
>
I will update the `AARCH64_PVTIME_IPA_MAX_SIZE` defintion with `SZ_64K`.
> > +#define AARCH64_PROTECTED_VM_FW_MAX_SIZE (0x200000)
>
> This definitely looks like something that shouldn't be there. Yet.
>
I agree, I will remove it for the moment.
> > +#define AARCH64_PVTIME_IPA_START (ARM_MEMORY_AREA - \
> > + AARCH64_PROTECTED_VM_FW_MAX_SIZE - \
> > + AARCH64_PVTIME_IPA_MAX_SIZE)
> > +#define AARCH64_PVTIME_SIZE (64)
> >
> > #define ARM_LOMAP_MAX_MEMORY ((1ULL << 32) - ARM_MEMORY_AREA)
> > #define ARM_HIMAP_MAX_MEMORY ((1ULL << 40) - ARM_MEMORY_AREA)
> > diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c
> > index 6a2408c..84ac1e9 100644
> > --- a/arm/kvm-cpu.c
> > +++ b/arm/kvm-cpu.c
> > @@ -116,6 +116,13 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm
> > *kvm, unsigned long cpu_id)
> > die("Unable to find matching target");
> > }
> >
> > + /* Populate the vcpu structure. */
> > + vcpu->kvm = kvm;
> > + vcpu->cpu_id = cpu_id;
> > + vcpu->cpu_type = vcpu_init.target;
> > + vcpu->cpu_compatible = target->compatible;
> > + vcpu->is_running = true;
> > +
> > if (err || target->init(vcpu))
> > die("Unable to initialise vcpu");
> >
> > @@ -125,13 +132,6 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm
> > *kvm, unsigned long cpu_id)
> > vcpu->ring = (void *)vcpu->kvm_run +
> > (coalesced_offset * PAGE_SIZE);
> >
> > - /* Populate the vcpu structure. */
> > - vcpu->kvm = kvm;
> > - vcpu->cpu_id = cpu_id;
> > - vcpu->cpu_type = vcpu_init.target;
> > - vcpu->cpu_compatible = target->compatible;
> > - vcpu->is_running = true;
> > -
>
> What is the reason for moving these assignments around?
>
The setup of the pvtime is done during the vcpu initialisation and I
need to access the kvm structure during that time.
> > if (kvm_cpu__configure_features(vcpu))
> > die("Unable to configure requested vcpu features");
>
> Thanks,
>
> M.
> --
> Jazz is not dead. It just smells funny...
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