| Message ID | 20220104194918.373612-4-rananta@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: arm64: Add support for hypercall services selection | expand |
Hi Raghu, On Tue, Jan 4, 2022 at 11:49 AM Raghavendra Rao Ananta <rananta@google.com> wrote: > > Introduce the KVM ARM64 capability, KVM_CAP_ARM_HVC_FW_REG_BMAP, > to indicate the support for psuedo-firmware bitmap extension. > Each of these registers holds a feature-set exposed to the guest > in the form of a bitmap. If supported, a simple 'read' of the > capability should return the number of psuedo-firmware registers > supported. User-space can utilize this to discover the registers. > It can further explore or modify the features using the classical > GET/SET_ONE_REG interface. > > Signed-off-by: Raghavendra Rao Ananta <rananta@google.com> > --- > Documentation/virt/kvm/api.rst | 21 +++++++++++++++++++++ > include/uapi/linux/kvm.h | 1 + > 2 files changed, 22 insertions(+) > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > index aeeb071c7688..646176537f2c 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -6925,6 +6925,27 @@ indicated by the fd to the VM this is called on. > This is intended to support intra-host migration of VMs between userspace VMMs, > upgrading the VMM process without interrupting the guest. > > +7.30 KVM_CAP_ARM_HVC_FW_REG_BMAP IMHO, instead of including its format of the register in the name, including its purpose/function in the name might be better. e.g. KVM_CAP_ARM_HVC_FEATURE_REG ? (Feature fields don't necessarily have to be in a bitmap format if they don't fit well although I'm not sure if we have such fields.) > +-------------------------------- > + > +:Architectures: arm64 > +:Parameters: None > +:Returns: Number of psuedo-firmware registers supported Looking at patch-4, the return value of this would be the number of pseudo-firmware *bitmap* registers supported. BTW, "4.68 KVM_SET_ONE_REG" in the doc uses the word "arm64 firmware pseudo-registers". It would be nicer to use the same term. > + > +This capability indicates that KVM for arm64 supports the psuedo-firmware > +register bitmap extension. Each of these registers represent the features > +supported by a particular type in the form of a bitmap. By default, these > +registers are set with the upper limit of the features that are supported. > + > +The registers can be accessed via the standard SET_ONE_REG and KVM_GET_ONE_REG > +interfaces. The user-space is expected to read the number of these registers > +available by reading KVM_CAP_ARM_HVC_FW_REG_BMAP, read the current bitmap > +configuration via GET_ONE_REG for each register, and then write back the > +desired bitmap of features that it wishes the guest to see via SET_ONE_REG. > + > +Note that KVM doesn't allow the user-space to modify these registers after > +the VM (any of the vCPUs) has started running. Since even if KVM_RUN fails, and the VM hasn't started yet, it will get immutable. So, "after any of the vCPUs run KVM_RUN." might be more clear ? Thanks, Reiji > + > 8. Other capabilities. > ====================== > > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index 1daa45268de2..209b43dbbc3c 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -1131,6 +1131,7 @@ struct kvm_ppc_resize_hpt { > #define KVM_CAP_EXIT_ON_EMULATION_FAILURE 204 > #define KVM_CAP_ARM_MTE 205 > #define KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM 206 > +#define KVM_CAP_ARM_HVC_FW_REG_BMAP 207 > > #ifdef KVM_CAP_IRQ_ROUTING > > -- > 2.34.1.448.ga2b2bfdf31-goog >
On Fri, Jan 7, 2022 at 9:40 PM Reiji Watanabe <reijiw@google.com> wrote: > > Hi Raghu, > > On Tue, Jan 4, 2022 at 11:49 AM Raghavendra Rao Ananta > <rananta@google.com> wrote: > > > > Introduce the KVM ARM64 capability, KVM_CAP_ARM_HVC_FW_REG_BMAP, > > to indicate the support for psuedo-firmware bitmap extension. > > Each of these registers holds a feature-set exposed to the guest > > in the form of a bitmap. If supported, a simple 'read' of the > > capability should return the number of psuedo-firmware registers > > supported. User-space can utilize this to discover the registers. > > It can further explore or modify the features using the classical > > GET/SET_ONE_REG interface. > > > > Signed-off-by: Raghavendra Rao Ananta <rananta@google.com> > > --- > > Documentation/virt/kvm/api.rst | 21 +++++++++++++++++++++ > > include/uapi/linux/kvm.h | 1 + > > 2 files changed, 22 insertions(+) > > > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > > index aeeb071c7688..646176537f2c 100644 > > --- a/Documentation/virt/kvm/api.rst > > +++ b/Documentation/virt/kvm/api.rst > > @@ -6925,6 +6925,27 @@ indicated by the fd to the VM this is called on. > > This is intended to support intra-host migration of VMs between userspace VMMs, > > upgrading the VMM process without interrupting the guest. > > > > +7.30 KVM_CAP_ARM_HVC_FW_REG_BMAP > > IMHO, instead of including its format of the register in the name, > including its purpose/function in the name might be better. > e.g. KVM_CAP_ARM_HVC_FEATURE_REG ? > (Feature fields don't necessarily have to be in a bitmap format > if they don't fit well although I'm not sure if we have such fields.) > Well we do have registers, KVM_REG_ARM_PSCI_VERSION for instance, that's not covered by this CAP. But sure, I can explicitly add 'FEATURES' to the name. I also wanted to explicitly convey that we are covering the *bitmapped* firmware registers here. But not sure if appending 'BMAP' might give an impression that the CAP itself is bitmapped. Do you think KVM_CAP_ARM_HVC_BMAP_FEAT_REG is better? > > + > > +:Architectures: arm64 > > +:Parameters: None > > +:Returns: Number of psuedo-firmware registers supported > > Looking at patch-4, the return value of this would be the number of > pseudo-firmware *bitmap* registers supported. > BTW, "4.68 KVM_SET_ONE_REG" in the doc uses the word "arm64 firmware > pseudo-registers". It would be nicer to use the same term. > Nice catch. I'll fix it here in apr.rst. > > + > > +This capability indicates that KVM for arm64 supports the psuedo-firmware > > +register bitmap extension. Each of these registers represent the features > > +supported by a particular type in the form of a bitmap. By default, these > > +registers are set with the upper limit of the features that are supported. > > + > > +The registers can be accessed via the standard SET_ONE_REG and KVM_GET_ONE_REG > > +interfaces. The user-space is expected to read the number of these registers > > +available by reading KVM_CAP_ARM_HVC_FW_REG_BMAP, read the current bitmap > > +configuration via GET_ONE_REG for each register, and then write back the > > +desired bitmap of features that it wishes the guest to see via SET_ONE_REG. > > + > > +Note that KVM doesn't allow the user-space to modify these registers after > > +the VM (any of the vCPUs) has started running. > > Since even if KVM_RUN fails, and the VM hasn't started yet, > it will get immutable. So, "after any of the vCPUs run KVM_RUN." > might be more clear ? > Sure, that's probably more clear. I'll fix it. Regards, Raghavendra > Thanks, > Reiji > > > > > + > > 8. Other capabilities. > > ====================== > > > > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > > index 1daa45268de2..209b43dbbc3c 100644 > > --- a/include/uapi/linux/kvm.h > > +++ b/include/uapi/linux/kvm.h > > @@ -1131,6 +1131,7 @@ struct kvm_ppc_resize_hpt { > > #define KVM_CAP_EXIT_ON_EMULATION_FAILURE 204 > > #define KVM_CAP_ARM_MTE 205 > > #define KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM 206 > > +#define KVM_CAP_ARM_HVC_FW_REG_BMAP 207 > > > > #ifdef KVM_CAP_IRQ_ROUTING > > > > -- > > 2.34.1.448.ga2b2bfdf31-goog > >
On Mon, Jan 10, 2022 at 3:40 PM Raghavendra Rao Ananta <rananta@google.com> wrote: > > On Fri, Jan 7, 2022 at 9:40 PM Reiji Watanabe <reijiw@google.com> wrote: > > > > Hi Raghu, > > > > On Tue, Jan 4, 2022 at 11:49 AM Raghavendra Rao Ananta > > <rananta@google.com> wrote: > > > > > > Introduce the KVM ARM64 capability, KVM_CAP_ARM_HVC_FW_REG_BMAP, > > > to indicate the support for psuedo-firmware bitmap extension. > > > Each of these registers holds a feature-set exposed to the guest > > > in the form of a bitmap. If supported, a simple 'read' of the > > > capability should return the number of psuedo-firmware registers > > > supported. User-space can utilize this to discover the registers. > > > It can further explore or modify the features using the classical > > > GET/SET_ONE_REG interface. > > > > > > Signed-off-by: Raghavendra Rao Ananta <rananta@google.com> > > > --- > > > Documentation/virt/kvm/api.rst | 21 +++++++++++++++++++++ > > > include/uapi/linux/kvm.h | 1 + > > > 2 files changed, 22 insertions(+) > > > > > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > > > index aeeb071c7688..646176537f2c 100644 > > > --- a/Documentation/virt/kvm/api.rst > > > +++ b/Documentation/virt/kvm/api.rst > > > @@ -6925,6 +6925,27 @@ indicated by the fd to the VM this is called on. > > > This is intended to support intra-host migration of VMs between userspace VMMs, > > > upgrading the VMM process without interrupting the guest. > > > > > > +7.30 KVM_CAP_ARM_HVC_FW_REG_BMAP > > > > IMHO, instead of including its format of the register in the name, > > including its purpose/function in the name might be better. > > e.g. KVM_CAP_ARM_HVC_FEATURE_REG ? > > (Feature fields don't necessarily have to be in a bitmap format > > if they don't fit well although I'm not sure if we have such fields.) > > > Well we do have registers, KVM_REG_ARM_PSCI_VERSION for instance, > that's not covered by this CAP. But sure, I can explicitly add > 'FEATURES' to the name. I also wanted to explicitly convey that we are > covering the *bitmapped* firmware registers here. But not sure if > appending 'BMAP' might give an impression that the CAP itself is > bitmapped. > Do you think KVM_CAP_ARM_HVC_BMAP_FEAT_REG is better? Thank you for the explanation! That sounds better to me. Regards, Reiji > > > + > > > +:Architectures: arm64 > > > +:Parameters: None > > > +:Returns: Number of psuedo-firmware registers supported > > > > Looking at patch-4, the return value of this would be the number of > > pseudo-firmware *bitmap* registers supported. > > BTW, "4.68 KVM_SET_ONE_REG" in the doc uses the word "arm64 firmware > > pseudo-registers". It would be nicer to use the same term. > > > Nice catch. I'll fix it here in apr.rst. > > > + > > > +This capability indicates that KVM for arm64 supports the psuedo-firmware > > > +register bitmap extension. Each of these registers represent the features > > > +supported by a particular type in the form of a bitmap. By default, these > > > +registers are set with the upper limit of the features that are supported. > > > + > > > +The registers can be accessed via the standard SET_ONE_REG and KVM_GET_ONE_REG > > > +interfaces. The user-space is expected to read the number of these registers > > > +available by reading KVM_CAP_ARM_HVC_FW_REG_BMAP, read the current bitmap > > > +configuration via GET_ONE_REG for each register, and then write back the > > > +desired bitmap of features that it wishes the guest to see via SET_ONE_REG. > > > + > > > +Note that KVM doesn't allow the user-space to modify these registers after > > > +the VM (any of the vCPUs) has started running. > > > > Since even if KVM_RUN fails, and the VM hasn't started yet, > > it will get immutable. So, "after any of the vCPUs run KVM_RUN." > > might be more clear ? > > > Sure, that's probably more clear. I'll fix it. > > Regards, > Raghavendra > > > Thanks, > > Reiji > > > > > > > > > + > > > 8. Other capabilities. > > > ====================== > > > > > > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > > > index 1daa45268de2..209b43dbbc3c 100644 > > > --- a/include/uapi/linux/kvm.h > > > +++ b/include/uapi/linux/kvm.h > > > @@ -1131,6 +1131,7 @@ struct kvm_ppc_resize_hpt { > > > #define KVM_CAP_EXIT_ON_EMULATION_FAILURE 204 > > > #define KVM_CAP_ARM_MTE 205 > > > #define KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM 206 > > > +#define KVM_CAP_ARM_HVC_FW_REG_BMAP 207 > > > > > > #ifdef KVM_CAP_IRQ_ROUTING > > > > > > -- > > > 2.34.1.448.ga2b2bfdf31-goog > > >
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index aeeb071c7688..646176537f2c 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6925,6 +6925,27 @@ indicated by the fd to the VM this is called on. This is intended to support intra-host migration of VMs between userspace VMMs, upgrading the VMM process without interrupting the guest. +7.30 KVM_CAP_ARM_HVC_FW_REG_BMAP +-------------------------------- + +:Architectures: arm64 +:Parameters: None +:Returns: Number of psuedo-firmware registers supported + +This capability indicates that KVM for arm64 supports the psuedo-firmware +register bitmap extension. Each of these registers represent the features +supported by a particular type in the form of a bitmap. By default, these +registers are set with the upper limit of the features that are supported. + +The registers can be accessed via the standard SET_ONE_REG and KVM_GET_ONE_REG +interfaces. The user-space is expected to read the number of these registers +available by reading KVM_CAP_ARM_HVC_FW_REG_BMAP, read the current bitmap +configuration via GET_ONE_REG for each register, and then write back the +desired bitmap of features that it wishes the guest to see via SET_ONE_REG. + +Note that KVM doesn't allow the user-space to modify these registers after +the VM (any of the vCPUs) has started running. + 8. Other capabilities. ====================== diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 1daa45268de2..209b43dbbc3c 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1131,6 +1131,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_EXIT_ON_EMULATION_FAILURE 204 #define KVM_CAP_ARM_MTE 205 #define KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM 206 +#define KVM_CAP_ARM_HVC_FW_REG_BMAP 207 #ifdef KVM_CAP_IRQ_ROUTING
Introduce the KVM ARM64 capability, KVM_CAP_ARM_HVC_FW_REG_BMAP, to indicate the support for psuedo-firmware bitmap extension. Each of these registers holds a feature-set exposed to the guest in the form of a bitmap. If supported, a simple 'read' of the capability should return the number of psuedo-firmware registers supported. User-space can utilize this to discover the registers. It can further explore or modify the features using the classical GET/SET_ONE_REG interface. Signed-off-by: Raghavendra Rao Ananta <rananta@google.com> --- Documentation/virt/kvm/api.rst | 21 +++++++++++++++++++++ include/uapi/linux/kvm.h | 1 + 2 files changed, 22 insertions(+)