Re: [kvmarm] [PATCH v5 03/14] KVM: ARM: Initial skeleton to compile KVM support
On 01/15/2013 04:35 PM, Gleb Natapov wrote:
On Tue, Jan 15, 2013 at 02:43:26PM +0100, Alexander Graf wrote:
On 15.01.2013, at 14:32, Gleb Natapov wrote:
On Mon, Jan 14, 2013 at 05:17:31PM -0500, Christoffer Dall wrote:
On Mon, Jan 14, 2013 at 1:49 PM, Gleb Natapov wrote:
A couple of general question about ABI. If they were already answered
just refer me to the previous discussion.
On Tue, Jan 08, 2013 at 01:38:55PM -0500, Christoffer Dall wrote:
diff --git a/Documentation/virtual/kvm/api.txt
b/Documentation/virtual/kvm/api.txt
index a4df553..4237c27 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -293,7 +293,7 @@ kvm_run' (see below).
4.11 KVM_GET_REGS
Capability: basic
-Architectures: all
+Architectures: all except ARM
Type: vcpu ioctl
Parameters: struct kvm_regs (out)
Returns: 0 on success, -1 on error
@@ -314,7 +314,7 @@ struct kvm_regs {
4.12 KVM_SET_REGS
Capability: basic
-Architectures: all
+Architectures: all except ARM
Type: vcpu ioctl
Parameters: struct kvm_regs (in)
Returns: 0 on success, -1 on error
@@ -600,7 +600,7 @@ struct kvm_fpu {
4.24 KVM_CREATE_IRQCHIP
Why KVM_GET_REGS/KVM_SET_REGS are not usable for arm?
We use the ONE_REG API instead and we don't want to support two
separate APIs to user space.
I suppose fetching all registers is not anywhere on a fast path in
userspace :)
If it's ever going to be in a fast path, we will add MULTI_REG which will
feature an array of ONE_REG structs to fetch multiple registers at once.
And I hope it will not be. On x86 only the broken vmware PV
interface requires reading registers for emulation.
This reminds me the question I wanted to ask you about ONE_REG
interface. Why architecture is encoded in register name? Is architecture
implied by HW the code is running on anyway?
It provides for nice sanity checks. Also, 64 bits are quite a lot, so we
can easily waste a few bits for redundancy.
Alex
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Re: [kvmarm] [PATCH v5 03/14] KVM: ARM: Initial skeleton to compile KVM support
On Tue, Jan 15, 2013 at 02:43:26PM +0100, Alexander Graf wrote:
>
> On 15.01.2013, at 14:32, Gleb Natapov wrote:
>
> > On Mon, Jan 14, 2013 at 05:17:31PM -0500, Christoffer Dall wrote:
> >> On Mon, Jan 14, 2013 at 1:49 PM, Gleb Natapov wrote:
> >>> A couple of general question about ABI. If they were already answered
> >>> just refer me to the previous discussion.
> >>>
> >>> On Tue, Jan 08, 2013 at 01:38:55PM -0500, Christoffer Dall wrote:
> diff --git a/Documentation/virtual/kvm/api.txt
> b/Documentation/virtual/kvm/api.txt
> index a4df553..4237c27 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -293,7 +293,7 @@ kvm_run' (see below).
> 4.11 KVM_GET_REGS
>
> Capability: basic
> -Architectures: all
> +Architectures: all except ARM
> Type: vcpu ioctl
> Parameters: struct kvm_regs (out)
> Returns: 0 on success, -1 on error
> @@ -314,7 +314,7 @@ struct kvm_regs {
> 4.12 KVM_SET_REGS
>
> Capability: basic
> -Architectures: all
> +Architectures: all except ARM
> Type: vcpu ioctl
> Parameters: struct kvm_regs (in)
> Returns: 0 on success, -1 on error
> @@ -600,7 +600,7 @@ struct kvm_fpu {
> 4.24 KVM_CREATE_IRQCHIP
> >>> Why KVM_GET_REGS/KVM_SET_REGS are not usable for arm?
> >>>
> >>
> >> We use the ONE_REG API instead and we don't want to support two
> >> separate APIs to user space.
> >>
> > I suppose fetching all registers is not anywhere on a fast path in
> > userspace :)
>
> If it's ever going to be in a fast path, we will add MULTI_REG which will
> feature an array of ONE_REG structs to fetch multiple registers at once.
>
And I hope it will not be. On x86 only the broken vmware PV
interface requires reading registers for emulation.
This reminds me the question I wanted to ask you about ONE_REG
interface. Why architecture is encoded in register name? Is architecture
implied by HW the code is running on anyway?
--
Gleb.
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Re: [kvmarm] [PATCH v5 03/14] KVM: ARM: Initial skeleton to compile KVM support
On 15.01.2013, at 14:32, Gleb Natapov wrote:
> On Mon, Jan 14, 2013 at 05:17:31PM -0500, Christoffer Dall wrote:
>> On Mon, Jan 14, 2013 at 1:49 PM, Gleb Natapov wrote:
>>> A couple of general question about ABI. If they were already answered
>>> just refer me to the previous discussion.
>>>
>>> On Tue, Jan 08, 2013 at 01:38:55PM -0500, Christoffer Dall wrote:
diff --git a/Documentation/virtual/kvm/api.txt
b/Documentation/virtual/kvm/api.txt
index a4df553..4237c27 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -293,7 +293,7 @@ kvm_run' (see below).
4.11 KVM_GET_REGS
Capability: basic
-Architectures: all
+Architectures: all except ARM
Type: vcpu ioctl
Parameters: struct kvm_regs (out)
Returns: 0 on success, -1 on error
@@ -314,7 +314,7 @@ struct kvm_regs {
4.12 KVM_SET_REGS
Capability: basic
-Architectures: all
+Architectures: all except ARM
Type: vcpu ioctl
Parameters: struct kvm_regs (in)
Returns: 0 on success, -1 on error
@@ -600,7 +600,7 @@ struct kvm_fpu {
4.24 KVM_CREATE_IRQCHIP
>>> Why KVM_GET_REGS/KVM_SET_REGS are not usable for arm?
>>>
>>
>> We use the ONE_REG API instead and we don't want to support two
>> separate APIs to user space.
>>
> I suppose fetching all registers is not anywhere on a fast path in
> userspace :)
If it's ever going to be in a fast path, we will add MULTI_REG which will
feature an array of ONE_REG structs to fetch multiple registers at once.
Alex
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