Re: [Xen-devel] [PATCH v8 08/16] x86: implement set value flow for MBA

2017-10-16 Thread Yi Sun 
On 17-10-16 06:49:49, Jan Beulich wrote:
> >>> On 16.10.17 at 05:04,  wrote:
> > This patch implements set value flow for MBA including its callback
> > function and domctl interface.
> > 
> > Signed-off-by: Yi Sun 
> 
> Reviewed-by: Jan Beulich 
> 
> > v8:
> > - restore some unnecessary changes in 'cat_check_cbm'.
> >   (suggested by Jan Beulich)
> 
> This reads as if you did exactly the opposite thing of what you
> actually did.
> 
> > +static bool mba_sanitize_thrtl(const struct feat_node *feat, uint32_t 
> > *thrtl)
> > +{
> > +if ( *thrtl > feat->mba.thrtl_max )
> > +return false;
> 
> Wouldn't it be better to do this check after ...
> 
> > +/*
> > + * Per SDM (chapter "Memory Bandwidth Allocation Configuration"):
> > + * 1. Linear mode: In the linear mode the input precision is defined
> > + *as 100-(MBA_MAX). For instance, if the MBA_MAX value is 90, the
> > + *input precision is 10%. Values not an even multiple of the
> > + *precision (e.g., 12%) will be rounded down (e.g., to 10% delay
> > + *applied).
> > + * 2. Non-linear mode: Input delay values are powers-of-two from zero
> > + *to the MBA_MAX value from CPUID. In this case any values not a
> > + *power of two will be rounded down the next nearest power of two.
> > + */
> > +if ( feat->mba.linear )
> > +*thrtl -= *thrtl % (100 - feat->mba.thrtl_max);
> > +else
> > +{
> > +/* Not power of 2. */
> > +if ( *thrtl & (*thrtl - 1) )
> > +*thrtl = 1 << (fls(*thrtl) - 1);
> > +}
> 
> ... these adjustments? That way someone specifying e.g. a linear
> value of 95% would get 90% just like for 85% (s)he would get
> 80%.
> 
> > +return true;
> 
> If so, the return statement could simply become
> 
> return *thrtl <= feat->mba.thrtl_max;
> 
> My R-b also applies if you decide to make this change.
> 
Thank you for the suggestion! It is not worthy to send whole patch set out.
I will just update this patch.

> Jan

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Re: [Xen-devel] [PATCH v8 08/16] x86: implement set value flow for MBA

2017-10-16 Thread Jan Beulich 
>>> On 16.10.17 at 05:04,  wrote:
> This patch implements set value flow for MBA including its callback
> function and domctl interface.
> 
> Signed-off-by: Yi Sun 

Reviewed-by: Jan Beulich 

> v8:
> - restore some unnecessary changes in 'cat_check_cbm'.
>   (suggested by Jan Beulich)

This reads as if you did exactly the opposite thing of what you
actually did.

> +static bool mba_sanitize_thrtl(const struct feat_node *feat, uint32_t *thrtl)
> +{
> +if ( *thrtl > feat->mba.thrtl_max )
> +return false;

Wouldn't it be better to do this check after ...

> +/*
> + * Per SDM (chapter "Memory Bandwidth Allocation Configuration"):
> + * 1. Linear mode: In the linear mode the input precision is defined
> + *as 100-(MBA_MAX). For instance, if the MBA_MAX value is 90, the
> + *input precision is 10%. Values not an even multiple of the
> + *precision (e.g., 12%) will be rounded down (e.g., to 10% delay
> + *applied).
> + * 2. Non-linear mode: Input delay values are powers-of-two from zero
> + *to the MBA_MAX value from CPUID. In this case any values not a
> + *power of two will be rounded down the next nearest power of two.
> + */
> +if ( feat->mba.linear )
> +*thrtl -= *thrtl % (100 - feat->mba.thrtl_max);
> +else
> +{
> +/* Not power of 2. */
> +if ( *thrtl & (*thrtl - 1) )
> +*thrtl = 1 << (fls(*thrtl) - 1);
> +}

... these adjustments? That way someone specifying e.g. a linear
value of 95% would get 90% just like for 85% (s)he would get
80%.

> +return true;

If so, the return statement could simply become

return *thrtl <= feat->mba.thrtl_max;

My R-b also applies if you decide to make this change.

Jan


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[Xen-devel] [PATCH v8 08/16] x86: implement set value flow for MBA

2017-10-15 Thread Yi Sun 
This patch implements set value flow for MBA including its callback
function and domctl interface.

Signed-off-by: Yi Sun 
---
CC: Jan Beulich 
CC: Andrew Cooper 
CC: Wei Liu 
CC: Roger Pau Monné 
CC: Chao Peng 

v8:
- restore some unnecessary changes in 'cat_check_cbm'.
  (suggested by Jan Beulich)
- use 'fls()' but not 'flsl()'.
  (suggested by Jan Beulich)
- use plain '=' to assign value for thrtl in 'mba_sanitize_thrtl'.
  (suggested by Jan Beulich)
v7:
- change name of 'check_val' to 'sanitize'.
  (suggested by Jan Beulich)
- fix comments.
  (suggested by Jan Beulich)
- add parentheses and change '== 0' to '!'.
  (suggested by Jan Beulich)
- remove unnecessary check of 'mba.thrtl_max'.
  (suggested by Jan Beulich)
- remove unnecessary intermediate variable 'mod'.
  (suggested by Jan Beulich)
- refine an assignement sentence to use '&='.
  (suggested by Jan Beulich)
- change type of last parameter of 'sanitize' to 'uint32_t' and
  apply same change to 'cat_check_cbm'.
  (suggested by Jan Beulich)
v6:
- split co-exist features' values setting flow to a new patch.
  (suggested by Jan Beulich)
- restore codes related to 'mba_check_thrtl' and 'check_value'.
  (suggested by Jan Beulich)
v5:
- adjust position of 'cat_check_cbm' to not to make changes so big.
  (suggested by Roger Pau Monné)
- remove 'props' from 'struct cos_write_info'.
  (suggested by Roger Pau Monné)
- make a single return statement in 'mba_check_thrtl'.
  (suggested by Jan Beulich)
v4:
- remove 'ALLOC_' from macro names.
  (suggested by Roger Pau Monné)
- join two checks into a single if.
  (suggested by Roger Pau Monné)
- remove redundant local variable 'array_len'.
  (suggested by Roger Pau Monné)
v3:
- modify commit message to make it clear.
  (suggested by Roger Pau Monné)
- modify functionality of 'check_val' to make it simple to only check value.
  Change the last parameter type from 'unsigned long *' to 'unsigned long'.
  (suggested by Roger Pau Monné)
- call rdmsrl to get value just written into MSR for MBA. Because HW can
  automatically change input value to what it wants.
  (suggested by Roger Pau Monné)
- change type of 'write_msr' to 'uint32_t' to return the value actually
  written into MSR. Then, change 'do_write_psr_msrs' to set the returned
  value into 'cos_reg_val[]'
- move the declaration of 'j' into loop in 'do_write_psr_msrs'.
  (suggested by Roger Pau Monné)
- change 'mba_info' to 'mba'.
  (suggested by Roger Pau Monné)
- change 'cat_info' to 'cat'.
  (suggested by Roger Pau Monné)
- rename 'psr_cat/PSR_CAT' to 'psr_alloc/PSR_ALLOC' and remove 'op/OP'
  from name.
  (suggested by Roger Pau Monné)
- change 'PSR_VAL_TYPE_MBA' to 'PSR_TYPE_MBA_THRTL'.
  (suggested by Roger Pau Monné)
v2:
- remove linear mode 'thrtl_max' check in 'mba_check_thrtl' because it has
  been checked in 'mba_init_feature'.
  (suggested by Chao Peng)
- for non-linear mode, check if '*thrtl' is not 0 in 'mba_check_thrtl'. If
  it is 0, we do not need to change it.
  (suggested by Chao Peng)
- move comments to explain changes of 'cos_write_info' from psr.c to commit
  message.
  (suggested by Chao Peng)
---
 xen/arch/x86/domctl.c   |  6 ++
 xen/arch/x86/psr.c  | 49 +
 xen/include/public/domctl.h |  1 +
 3 files changed, 52 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index b726eae..4bca15d 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -1465,6 +1465,12 @@ long arch_do_domctl(
   PSR_TYPE_L2_CBM);
 break;
 
+case XEN_DOMCTL_PSR_SET_MBA_THRTL:
+ret = psr_set_val(d, domctl->u.psr_alloc.target,
+  domctl->u.psr_alloc.data,
+  PSR_TYPE_MBA_THRTL);
+break;
+
 #define domctl_psr_get_val(d, domctl, type, copyback) ({\
 uint32_t v_;\
 int r_ = psr_get_val((d), (domctl)->u.psr_alloc.target, \
diff --git a/xen/arch/x86/psr.c b/xen/arch/x86/psr.c
index 549f21b..04dd4a1 100644
--- a/xen/arch/x86/psr.c
+++ b/xen/arch/x86/psr.c
@@ -138,6 +138,12 @@ static const struct feat_props {
 
 /* write_msr is used to write out feature MSR register. */
 void (*write_msr)(unsigned int cos, uint32_t val, enum psr_type type);
+
+/*
+ * sanitize is used to check if input val fulfills SDM requirement.
+ * And change it to valid value if SDM allows.
+ */
+bool (*sanitize)(const struct feat_node *feat, uint32_t *val);
 }