> > I notice there are several call sites using the safe version w/o
> > checking the return value, should the unsafe version be a better
> > choice in such cases?
>
> Depends. The safe version does not emit a warning on fail. So if the
> callsite truly does not care about the error it's fine.
Ri
On Fri, Sep 22 2023 at 08:16, Xin3 Li wrote:
>> > > +static __always_inline void __wrmsrns(u32 msr, u32 low, u32 high)
>> >
>> > Shouldn't this be named wrmsrns_safe since it has exception handling,
>> > similar
>> to
>> > the current wrmsrl_safe.
>> >
>>
>> Both safe and unsafe versions have exc
> > > +static __always_inline void __wrmsrns(u32 msr, u32 low, u32 high)
> >
> > Shouldn't this be named wrmsrns_safe since it has exception handling,
> > similar
> to
> > the current wrmsrl_safe.
> >
>
> Both safe and unsafe versions have exception handling, while the safe
> version returns an i
On 20.09.23 17:00, Peter Zijlstra wrote:
On Fri, Sep 15, 2023 at 02:16:50AM +0100, andrew.coop...@citrix.com wrote:
Juergen has already done the work to delete one of these two patching
mechanisms and replace it with the other.
https://lore.kernel.org/lkml/a32e211f-4add-4fb2-9e5a-480ae9b9b...@
On Fri, Sep 15, 2023 at 02:16:50AM +0100, andrew.coop...@citrix.com wrote:
> Juergen has already done the work to delete one of these two patching
> mechanisms and replace it with the other.
>
> https://lore.kernel.org/lkml/a32e211f-4add-4fb2-9e5a-480ae9b9b...@suse.com/
>
> Unfortunately, it's o
On 14.09.23 г. 7:47 ч., Xin Li wrote:
Add an always inline API __wrmsrns() to embed the WRMSRNS instruction
into the code.
Tested-by: Shan Kang
Signed-off-by: Xin Li
---
arch/x86/include/asm/msr.h | 18 ++
1 file changed, 18 insertions(+)
diff --git a/arch/x86/include/as
> > +static __always_inline void __wrmsrns(u32 msr, u32 low, u32 high)
>
> Shouldn't this be named wrmsrns_safe since it has exception handling, similar
> to
> the current wrmsrl_safe.
>
Both safe and unsafe versions have exception handling, while the safe
version returns an integer to its call
On 15.09.23 03:16, andrew.coop...@citrix.com wrote:
On 15/09/2023 2:01 am, H. Peter Anvin wrote:
The whole bit with alternatives and pvops being separate is a major
maintainability problem, and honestly it never made any sense in the
first place. Never have two mechanisms to do one job; it makes
On 9/14/23 18:46, andrew.coop...@citrix.com wrote:
On 15/09/2023 1:38 am, H. Peter Anvin wrote:
On 9/14/23 17:33, andrew.coop...@citrix.com wrote:
It's an assumption about what "definitely won't" be paravirt in the
future.
XenPV stack handling is almost-FRED-like and has been for the better
p
On 15/09/2023 1:38 am, H. Peter Anvin wrote:
> On 9/14/23 17:33, andrew.coop...@citrix.com wrote:
>>
>> It's an assumption about what "definitely won't" be paravirt in the
>> future.
>>
>> XenPV stack handling is almost-FRED-like and has been for the better
>> part of two decades.
>>
>> You frequen
On 15/09/2023 2:01 am, H. Peter Anvin wrote:
> The whole bit with alternatives and pvops being separate is a major
> maintainability problem, and honestly it never made any sense in the
> first place. Never have two mechanisms to do one job; it makes it
> harder to grok their interactions.
This bi
WRMSR has one complexity that most other PV-ops don't, and that's the
exception table reference for the instruction itself.
In a theoretical future ought to look like:
mov$msr, %ecx
mov$lo, %eax
mov$hi, %edx
1: {call paravirt_blah(%rip) | cs...cs wrmsr | cs...cs wrmsr
On Fri, Sep 15 2023 at 00:46, andrew wrote:
> On 15/09/2023 12:00 am, Thomas Gleixner wrote:
> What I meant was "there should be the two top-level APIs, and under the
> covers they DTRT". Part of doing the right thing is to wire up paravirt
> for configs where that is specified.
>
> Anything else
On 9/14/23 17:33, andrew.coop...@citrix.com wrote:
It's an assumption about what "definitely won't" be paravirt in the future.
XenPV stack handling is almost-FRED-like and has been for the better
part of two decades.
You frequently complain that there's too much black magic holding XenPV
toget
On 15/09/2023 1:12 am, Thomas Gleixner wrote:
> On Fri, Sep 15 2023 at 00:46, andrew wrote:
>> On 15/09/2023 12:00 am, Thomas Gleixner wrote:
>>> So no. I'm fundamentally disagreeing with your recommendation. The way
>>> forward is:
>>>
>>> 1) Provide the native variant for wrmsrns(), i.e. rename
On Fri, Sep 15 2023 at 00:46, andrew wrote:
> On 15/09/2023 12:00 am, Thomas Gleixner wrote:
>> So no. I'm fundamentally disagreeing with your recommendation. The way
>> forward is:
>>
>> 1) Provide the native variant for wrmsrns(), i.e. rename the proposed
>> wrmsrns() to native_wrmsr_ns()
On 15/09/2023 12:00 am, Thomas Gleixner wrote:
>> and despite what Juergen said, I'm going to recommend that you do wire
>> this through the paravirt infrastructure, for the benefit of regular
>> users having a nice API, not because XenPV is expecting to do something
>> wildly different here.
> I f
On September 14, 2023 4:00:39 PM PDT, Thomas Gleixner
wrote:
>Andrew!
>
>On Thu, Sep 14 2023 at 15:05, andrew wrote:
>> On 14/09/2023 5:47 am, Xin Li wrote:
>>> +static __always_inline void wrmsrns(u32 msr, u64 val)
>>> +{
>>> + __wrmsrns(msr, val, val >> 32);
>>> +}
>>
>> This API works in ter
Andrew!
On Thu, Sep 14 2023 at 15:05, andrew wrote:
> On 14/09/2023 5:47 am, Xin Li wrote:
>> +static __always_inline void wrmsrns(u32 msr, u64 val)
>> +{
>> +__wrmsrns(msr, val, val >> 32);
>> +}
>
> This API works in terms of this series where every WRMSRNS is hidden
> behind a FRED check, b
On 14/09/2023 5:47 am, Xin Li wrote:
> Add an always inline API __wrmsrns() to embed the WRMSRNS instruction
> into the code.
>
> Tested-by: Shan Kang
> Signed-off-by: Xin Li
> ---
> arch/x86/include/asm/msr.h | 18 ++
> 1 file changed, 18 insertions(+)
>
> diff --git a/arch/x86/
On 14/09/2023 7:02 am, Juergen Gross wrote:
> On 14.09.23 06:47, Xin Li wrote:
>> Add an always inline API __wrmsrns() to embed the WRMSRNS instruction
>> into the code.
>>
>> Tested-by: Shan Kang
>> Signed-off-by: Xin Li
>
> In order to avoid having to add paravirt support for WRMSRNS I think
>
On 14.09.23 06:47, Xin Li wrote:
Add an always inline API __wrmsrns() to embed the WRMSRNS instruction
into the code.
Tested-by: Shan Kang
Signed-off-by: Xin Li
In order to avoid having to add paravirt support for WRMSRNS I think
xen_init_capabilities() should gain:
+ setup_clear_cpu_
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