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[PATCH v5 1/2] xen/domain: introduce common hardware emulation flags

dmkhn@proton.me posted 2 patches 5 months ago
[PATCH v5 1/2] xen/domain: introduce common hardware emulation flags
Posted by dmkhn@proton.me 5 months ago 
From: Denis Mukhin <dmukhin@ford.com>

Add common emulation_flags for configuring domain emulation features.

Print d->emulation_flags from 'q' keyhandler for better traceability while
debugging.

Signed-off-by: Denis Mukhin <dmukhin@ford.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
---
Changes since v4:
- kept Stefano's R-b
---
 xen/arch/x86/domain.c             |  2 +-
 xen/arch/x86/domctl.c             |  2 +-
 xen/arch/x86/include/asm/domain.h | 25 +++++++++++--------------
 xen/common/keyhandler.c           |  1 +
 xen/include/xen/sched.h           |  2 ++
 5 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 7536b6c871..0363ccb384 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -831,7 +831,7 @@ int arch_domain_create(struct domain *d,
                emflags);
         return -EOPNOTSUPP;
     }
-    d->arch.emulation_flags = emflags;
+    d->emulation_flags = emflags;
 
 #ifdef CONFIG_PV32
     HYPERVISOR_COMPAT_VIRT_START(d) =
diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index 3044f706de..37d848f683 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -144,7 +144,7 @@ void arch_get_domain_info(const struct domain *d,
     if ( paging_mode_hap(d) )
         info->flags |= XEN_DOMINF_hap;
 
-    info->arch_config.emulation_flags = d->arch.emulation_flags;
+    info->arch_config.emulation_flags = d->emulation_flags;
     info->gpaddr_bits = hap_paddr_bits;
 }
 
diff --git a/xen/arch/x86/include/asm/domain.h b/xen/arch/x86/include/asm/domain.h
index 8c0dea12a5..eafd5cfc90 100644
--- a/xen/arch/x86/include/asm/domain.h
+++ b/xen/arch/x86/include/asm/domain.h
@@ -455,9 +455,6 @@ struct arch_domain
 
     /* Don't unconditionally inject #GP for unhandled MSRs. */
     bool msr_relaxed;
-
-    /* Emulated devices enabled bitmap. */
-    uint32_t emulation_flags;
 } __cacheline_aligned;
 
 #ifdef CONFIG_HVM
@@ -494,17 +491,17 @@ struct arch_domain
                                  X86_EMU_PIT | X86_EMU_USE_PIRQ |       \
                                  X86_EMU_VPCI)
 
-#define has_vlapic(d)      (!!((d)->arch.emulation_flags & X86_EMU_LAPIC))
-#define has_vhpet(d)       (!!((d)->arch.emulation_flags & X86_EMU_HPET))
-#define has_vpm(d)         (!!((d)->arch.emulation_flags & X86_EMU_PM))
-#define has_vrtc(d)        (!!((d)->arch.emulation_flags & X86_EMU_RTC))
-#define has_vioapic(d)     (!!((d)->arch.emulation_flags & X86_EMU_IOAPIC))
-#define has_vpic(d)        (!!((d)->arch.emulation_flags & X86_EMU_PIC))
-#define has_vvga(d)        (!!((d)->arch.emulation_flags & X86_EMU_VGA))
-#define has_viommu(d)      (!!((d)->arch.emulation_flags & X86_EMU_IOMMU))
-#define has_vpit(d)        (!!((d)->arch.emulation_flags & X86_EMU_PIT))
-#define has_pirq(d)        (!!((d)->arch.emulation_flags & X86_EMU_USE_PIRQ))
-#define has_vpci(d)        (!!((d)->arch.emulation_flags & X86_EMU_VPCI))
+#define has_vlapic(d)      (!!((d)->emulation_flags & X86_EMU_LAPIC))
+#define has_vhpet(d)       (!!((d)->emulation_flags & X86_EMU_HPET))
+#define has_vpm(d)         (!!((d)->emulation_flags & X86_EMU_PM))
+#define has_vrtc(d)        (!!((d)->emulation_flags & X86_EMU_RTC))
+#define has_vioapic(d)     (!!((d)->emulation_flags & X86_EMU_IOAPIC))
+#define has_vpic(d)        (!!((d)->emulation_flags & X86_EMU_PIC))
+#define has_vvga(d)        (!!((d)->emulation_flags & X86_EMU_VGA))
+#define has_viommu(d)      (!!((d)->emulation_flags & X86_EMU_IOMMU))
+#define has_vpit(d)        (!!((d)->emulation_flags & X86_EMU_PIT))
+#define has_pirq(d)        (!!((d)->emulation_flags & X86_EMU_USE_PIRQ))
+#define has_vpci(d)        (!!((d)->emulation_flags & X86_EMU_VPCI))
 
 #define gdt_ldt_pt_idx(v) \
       ((v)->vcpu_id >> (PAGETABLE_ORDER - GDT_LDT_VCPU_SHIFT))
diff --git a/xen/common/keyhandler.c b/xen/common/keyhandler.c
index 0bb842ec00..cd731452ba 100644
--- a/xen/common/keyhandler.c
+++ b/xen/common/keyhandler.c
@@ -306,6 +306,7 @@ static void cf_check dump_domains(unsigned char key)
             if ( test_bit(i, &d->watchdog_inuse_map) )
                 printk("    watchdog %d expires in %d seconds\n",
                        i, (u32)((d->watchdog_timer[i].expires - NOW()) >> 30));
+        printk("    emulation_flags %#x\n", d->emulation_flags);
 
         arch_dump_domain_info(d);
 
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index b17aada5f5..1393923986 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -651,6 +651,8 @@ struct domain
     unsigned int num_llc_colors;
     const unsigned int *llc_colors;
 #endif
+
+    uint32_t emulation_flags;
 } __aligned(PAGE_SIZE);
 
 static inline struct page_list_head *page_to_list(
-- 
2.34.1
Re: [PATCH v5 1/2] xen/domain: introduce common hardware emulation flags
Posted by Roger Pau Monné 4 months, 4 weeks ago 
On Mon, Jun 02, 2025 at 07:17:30PM +0000, dmkhn@proton.me wrote:
> From: Denis Mukhin <dmukhin@ford.com>
> 
> Add common emulation_flags for configuring domain emulation features.
> 
> Print d->emulation_flags from 'q' keyhandler for better traceability while
> debugging.
> 
> Signed-off-by: Denis Mukhin <dmukhin@ford.com>
> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
> ---
> Changes since v4:
> - kept Stefano's R-b
> ---
>  xen/arch/x86/domain.c             |  2 +-
>  xen/arch/x86/domctl.c             |  2 +-
>  xen/arch/x86/include/asm/domain.h | 25 +++++++++++--------------
>  xen/common/keyhandler.c           |  1 +
>  xen/include/xen/sched.h           |  2 ++
>  5 files changed, 16 insertions(+), 16 deletions(-)
> 
> diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
> index 7536b6c871..0363ccb384 100644
> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -831,7 +831,7 @@ int arch_domain_create(struct domain *d,
>                 emflags);
>          return -EOPNOTSUPP;
>      }
> -    d->arch.emulation_flags = emflags;
> +    d->emulation_flags = emflags;
>  
>  #ifdef CONFIG_PV32
>      HYPERVISOR_COMPAT_VIRT_START(d) =
> diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
> index 3044f706de..37d848f683 100644
> --- a/xen/arch/x86/domctl.c
> +++ b/xen/arch/x86/domctl.c
> @@ -144,7 +144,7 @@ void arch_get_domain_info(const struct domain *d,
>      if ( paging_mode_hap(d) )
>          info->flags |= XEN_DOMINF_hap;
>  
> -    info->arch_config.emulation_flags = d->arch.emulation_flags;
> +    info->arch_config.emulation_flags = d->emulation_flags;
>      info->gpaddr_bits = hap_paddr_bits;
>  }
>  
> diff --git a/xen/arch/x86/include/asm/domain.h b/xen/arch/x86/include/asm/domain.h
> index 8c0dea12a5..eafd5cfc90 100644
> --- a/xen/arch/x86/include/asm/domain.h
> +++ b/xen/arch/x86/include/asm/domain.h
> @@ -455,9 +455,6 @@ struct arch_domain
>  
>      /* Don't unconditionally inject #GP for unhandled MSRs. */
>      bool msr_relaxed;
> -
> -    /* Emulated devices enabled bitmap. */
> -    uint32_t emulation_flags;
>  } __cacheline_aligned;
>  
>  #ifdef CONFIG_HVM
> @@ -494,17 +491,17 @@ struct arch_domain
>                                   X86_EMU_PIT | X86_EMU_USE_PIRQ |       \
>                                   X86_EMU_VPCI)
>  
> -#define has_vlapic(d)      (!!((d)->arch.emulation_flags & X86_EMU_LAPIC))
> -#define has_vhpet(d)       (!!((d)->arch.emulation_flags & X86_EMU_HPET))
> -#define has_vpm(d)         (!!((d)->arch.emulation_flags & X86_EMU_PM))
> -#define has_vrtc(d)        (!!((d)->arch.emulation_flags & X86_EMU_RTC))
> -#define has_vioapic(d)     (!!((d)->arch.emulation_flags & X86_EMU_IOAPIC))
> -#define has_vpic(d)        (!!((d)->arch.emulation_flags & X86_EMU_PIC))
> -#define has_vvga(d)        (!!((d)->arch.emulation_flags & X86_EMU_VGA))
> -#define has_viommu(d)      (!!((d)->arch.emulation_flags & X86_EMU_IOMMU))
> -#define has_vpit(d)        (!!((d)->arch.emulation_flags & X86_EMU_PIT))
> -#define has_pirq(d)        (!!((d)->arch.emulation_flags & X86_EMU_USE_PIRQ))
> -#define has_vpci(d)        (!!((d)->arch.emulation_flags & X86_EMU_VPCI))
> +#define has_vlapic(d)      (!!((d)->emulation_flags & X86_EMU_LAPIC))
> +#define has_vhpet(d)       (!!((d)->emulation_flags & X86_EMU_HPET))
> +#define has_vpm(d)         (!!((d)->emulation_flags & X86_EMU_PM))
> +#define has_vrtc(d)        (!!((d)->emulation_flags & X86_EMU_RTC))
> +#define has_vioapic(d)     (!!((d)->emulation_flags & X86_EMU_IOAPIC))
> +#define has_vpic(d)        (!!((d)->emulation_flags & X86_EMU_PIC))
> +#define has_vvga(d)        (!!((d)->emulation_flags & X86_EMU_VGA))
> +#define has_viommu(d)      (!!((d)->emulation_flags & X86_EMU_IOMMU))
> +#define has_vpit(d)        (!!((d)->emulation_flags & X86_EMU_PIT))
> +#define has_pirq(d)        (!!((d)->emulation_flags & X86_EMU_USE_PIRQ))
> +#define has_vpci(d)        (!!((d)->emulation_flags & X86_EMU_VPCI))
>  
>  #define gdt_ldt_pt_idx(v) \
>        ((v)->vcpu_id >> (PAGETABLE_ORDER - GDT_LDT_VCPU_SHIFT))
> diff --git a/xen/common/keyhandler.c b/xen/common/keyhandler.c
> index 0bb842ec00..cd731452ba 100644
> --- a/xen/common/keyhandler.c
> +++ b/xen/common/keyhandler.c
> @@ -306,6 +306,7 @@ static void cf_check dump_domains(unsigned char key)
>              if ( test_bit(i, &d->watchdog_inuse_map) )
>                  printk("    watchdog %d expires in %d seconds\n",
>                         i, (u32)((d->watchdog_timer[i].expires - NOW()) >> 30));
> +        printk("    emulation_flags %#x\n", d->emulation_flags);

No strong opinion, but my preference would be to print those as
strings if possible, ie:

printk("    emulation_flags: %s%s%s...(%#x)\n",
       !d->emulation_flags ? "none " : "",
       has_vlapic(d) ? "vlapic " : "",
       has_vhpet(d) ? "hpet " : "",
       ...,
       d->emulation_flags);

Thanks, Roger.
Re: [PATCH v5 1/2] xen/domain: introduce common hardware emulation flags
Posted by dmkhn@proton.me 4 months, 3 weeks ago 
On Thu, Jun 05, 2025 at 11:08:07AM +0200, Roger Pau Monné wrote:
> On Mon, Jun 02, 2025 at 07:17:30PM +0000, dmkhn@proton.me wrote:
> > From: Denis Mukhin <dmukhin@ford.com>
> >
> > Add common emulation_flags for configuring domain emulation features.
> >
> > Print d->emulation_flags from 'q' keyhandler for better traceability while
> > debugging.
> >
> > Signed-off-by: Denis Mukhin <dmukhin@ford.com>
> > Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
> > ---
> > Changes since v4:
> > - kept Stefano's R-b
> > ---
> >  xen/arch/x86/domain.c             |  2 +-
> >  xen/arch/x86/domctl.c             |  2 +-
> >  xen/arch/x86/include/asm/domain.h | 25 +++++++++++--------------
> >  xen/common/keyhandler.c           |  1 +
> >  xen/include/xen/sched.h           |  2 ++
> >  5 files changed, 16 insertions(+), 16 deletions(-)
> >
> > diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
> > index 7536b6c871..0363ccb384 100644
> > --- a/xen/arch/x86/domain.c
> > +++ b/xen/arch/x86/domain.c
> > @@ -831,7 +831,7 @@ int arch_domain_create(struct domain *d,
> >                 emflags);
> >          return -EOPNOTSUPP;
> >      }
> > -    d->arch.emulation_flags = emflags;
> > +    d->emulation_flags = emflags;
> >
> >  #ifdef CONFIG_PV32
> >      HYPERVISOR_COMPAT_VIRT_START(d) =
> > diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
> > index 3044f706de..37d848f683 100644
> > --- a/xen/arch/x86/domctl.c
> > +++ b/xen/arch/x86/domctl.c
> > @@ -144,7 +144,7 @@ void arch_get_domain_info(const struct domain *d,
> >      if ( paging_mode_hap(d) )
> >          info->flags |= XEN_DOMINF_hap;
> >
> > -    info->arch_config.emulation_flags = d->arch.emulation_flags;
> > +    info->arch_config.emulation_flags = d->emulation_flags;
> >      info->gpaddr_bits = hap_paddr_bits;
> >  }
> >
> > diff --git a/xen/arch/x86/include/asm/domain.h b/xen/arch/x86/include/asm/domain.h
> > index 8c0dea12a5..eafd5cfc90 100644
> > --- a/xen/arch/x86/include/asm/domain.h
> > +++ b/xen/arch/x86/include/asm/domain.h
> > @@ -455,9 +455,6 @@ struct arch_domain
> >
> >      /* Don't unconditionally inject #GP for unhandled MSRs. */
> >      bool msr_relaxed;
> > -
> > -    /* Emulated devices enabled bitmap. */
> > -    uint32_t emulation_flags;
> >  } __cacheline_aligned;
> >
> >  #ifdef CONFIG_HVM
> > @@ -494,17 +491,17 @@ struct arch_domain
> >                                   X86_EMU_PIT | X86_EMU_USE_PIRQ |       \
> >                                   X86_EMU_VPCI)
> >
> > -#define has_vlapic(d)      (!!((d)->arch.emulation_flags & X86_EMU_LAPIC))
> > -#define has_vhpet(d)       (!!((d)->arch.emulation_flags & X86_EMU_HPET))
> > -#define has_vpm(d)         (!!((d)->arch.emulation_flags & X86_EMU_PM))
> > -#define has_vrtc(d)        (!!((d)->arch.emulation_flags & X86_EMU_RTC))
> > -#define has_vioapic(d)     (!!((d)->arch.emulation_flags & X86_EMU_IOAPIC))
> > -#define has_vpic(d)        (!!((d)->arch.emulation_flags & X86_EMU_PIC))
> > -#define has_vvga(d)        (!!((d)->arch.emulation_flags & X86_EMU_VGA))
> > -#define has_viommu(d)      (!!((d)->arch.emulation_flags & X86_EMU_IOMMU))
> > -#define has_vpit(d)        (!!((d)->arch.emulation_flags & X86_EMU_PIT))
> > -#define has_pirq(d)        (!!((d)->arch.emulation_flags & X86_EMU_USE_PIRQ))
> > -#define has_vpci(d)        (!!((d)->arch.emulation_flags & X86_EMU_VPCI))
> > +#define has_vlapic(d)      (!!((d)->emulation_flags & X86_EMU_LAPIC))
> > +#define has_vhpet(d)       (!!((d)->emulation_flags & X86_EMU_HPET))
> > +#define has_vpm(d)         (!!((d)->emulation_flags & X86_EMU_PM))
> > +#define has_vrtc(d)        (!!((d)->emulation_flags & X86_EMU_RTC))
> > +#define has_vioapic(d)     (!!((d)->emulation_flags & X86_EMU_IOAPIC))
> > +#define has_vpic(d)        (!!((d)->emulation_flags & X86_EMU_PIC))
> > +#define has_vvga(d)        (!!((d)->emulation_flags & X86_EMU_VGA))
> > +#define has_viommu(d)      (!!((d)->emulation_flags & X86_EMU_IOMMU))
> > +#define has_vpit(d)        (!!((d)->emulation_flags & X86_EMU_PIT))
> > +#define has_pirq(d)        (!!((d)->emulation_flags & X86_EMU_USE_PIRQ))
> > +#define has_vpci(d)        (!!((d)->emulation_flags & X86_EMU_VPCI))
> >
> >  #define gdt_ldt_pt_idx(v) \
> >        ((v)->vcpu_id >> (PAGETABLE_ORDER - GDT_LDT_VCPU_SHIFT))
> > diff --git a/xen/common/keyhandler.c b/xen/common/keyhandler.c
> > index 0bb842ec00..cd731452ba 100644
> > --- a/xen/common/keyhandler.c
> > +++ b/xen/common/keyhandler.c
> > @@ -306,6 +306,7 @@ static void cf_check dump_domains(unsigned char key)
> >              if ( test_bit(i, &d->watchdog_inuse_map) )
> >                  printk("    watchdog %d expires in %d seconds\n",
> >                         i, (u32)((d->watchdog_timer[i].expires - NOW()) >> 30));
> > +        printk("    emulation_flags %#x\n", d->emulation_flags);
> 
> No strong opinion, but my preference would be to print those as
> strings if possible, ie:
> 
> printk("    emulation_flags: %s%s%s...(%#x)\n",
>        !d->emulation_flags ? "none " : "",
>        has_vlapic(d) ? "vlapic " : "",
>        has_vhpet(d) ? "hpet " : "",
>        ...,
>        d->emulation_flags);

Thanks for suggestion.

There was the same feedback already:
  https://lore.kernel.org/xen-devel/aDd9Z3eY3RQgTTdy@kraken/

Is it OK to address it in the follow on change for both Arm and x86?

> 
> Thanks, Roger.
Re: [PATCH v5 1/2] xen/domain: introduce common hardware emulation flags
Posted by Jan Beulich 4 months, 4 weeks ago 
On 02.06.2025 21:17, dmkhn@proton.me wrote:
> From: Denis Mukhin <dmukhin@ford.com>
> 
> Add common emulation_flags for configuring domain emulation features.
> 
> Print d->emulation_flags from 'q' keyhandler for better traceability while
> debugging.
> 
> Signed-off-by: Denis Mukhin <dmukhin@ford.com>
> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

It's not becoming clear why this would want doing, nor in how far some of
the bits there may gain "common" meaning, too. Imo this kind of change is
meaningful only in a series where later the common-ness is also used.

Jan
Re: [PATCH v5 1/2] xen/domain: introduce common hardware emulation flags
Posted by dmkhn@proton.me 4 months, 4 weeks ago 
On Wed, Jun 04, 2025 at 12:36:17PM +0200, Jan Beulich wrote:
> On 02.06.2025 21:17, dmkhn@proton.me wrote:
> > From: Denis Mukhin <dmukhin@ford.com>
> >
> > Add common emulation_flags for configuring domain emulation features.
> >
> > Print d->emulation_flags from 'q' keyhandler for better traceability while
> > debugging.
> >
> > Signed-off-by: Denis Mukhin <dmukhin@ford.com>
> > Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
> 
> It's not becoming clear why this would want doing, nor in how far some of
> the bits there may gain "common" meaning, too. Imo this kind of change is
> meaningful only in a series where later the common-ness is also used.

I have a set of upcoming changes here:
  https://gitlab.com/xen-project/people/dmukhin/xen/-/tree/vuart-framework?ref_type=heads

Specifically,
 https://gitlab.com/xen-project/people/dmukhin/xen/-/commit/17f44d23c1904374963c4ec839bc8219041b5d26

enables the use of emulation_flags on Arm.

I can move this patch to the upcoming series, if needed, but looks like it is
OK to have it for Arm even now.

> 
> Jan
Re: [PATCH v5 1/2] xen/domain: introduce common hardware emulation flags
Posted by Jan Beulich 4 months, 4 weeks ago 
On 05.06.2025 03:17, dmkhn@proton.me wrote:
> On Wed, Jun 04, 2025 at 12:36:17PM +0200, Jan Beulich wrote:
>> On 02.06.2025 21:17, dmkhn@proton.me wrote:
>>> From: Denis Mukhin <dmukhin@ford.com>
>>>
>>> Add common emulation_flags for configuring domain emulation features.
>>>
>>> Print d->emulation_flags from 'q' keyhandler for better traceability while
>>> debugging.
>>>
>>> Signed-off-by: Denis Mukhin <dmukhin@ford.com>
>>> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
>>
>> It's not becoming clear why this would want doing, nor in how far some of
>> the bits there may gain "common" meaning, too. Imo this kind of change is
>> meaningful only in a series where later the common-ness is also used.
> 
> I have a set of upcoming changes here:
>   https://gitlab.com/xen-project/people/dmukhin/xen/-/tree/vuart-framework?ref_type=heads
> 
> Specifically,
>  https://gitlab.com/xen-project/people/dmukhin/xen/-/commit/17f44d23c1904374963c4ec839bc8219041b5d26
> 
> enables the use of emulation_flags on Arm.
> 
> I can move this patch to the upcoming series, if needed, but looks like it is
> OK to have it for Arm even now.

Prior to that series making it to a ready-to-be-committed state, it'll be
(effectively) dead code on Arm. Which strictly speaking Misra objects to.
I wonder if you, Stefano, considered that when giving your R-b.

Further - what about PPC and RISC-V?

Jan
Re: [PATCH v5 1/2] xen/domain: introduce common hardware emulation flags
Posted by dmkhn@proton.me 4 months, 3 weeks ago 
On Thu, Jun 05, 2025 at 08:44:30AM +0200, Jan Beulich wrote:
> On 05.06.2025 03:17, dmkhn@proton.me wrote:
> > On Wed, Jun 04, 2025 at 12:36:17PM +0200, Jan Beulich wrote:
> >> On 02.06.2025 21:17, dmkhn@proton.me wrote:
> >>> From: Denis Mukhin <dmukhin@ford.com>
> >>>
> >>> Add common emulation_flags for configuring domain emulation features.
> >>>
> >>> Print d->emulation_flags from 'q' keyhandler for better traceability while
> >>> debugging.
> >>>
> >>> Signed-off-by: Denis Mukhin <dmukhin@ford.com>
> >>> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
> >>
> >> It's not becoming clear why this would want doing, nor in how far some of
> >> the bits there may gain "common" meaning, too. Imo this kind of change is
> >> meaningful only in a series where later the common-ness is also used.
> >
> > I have a set of upcoming changes here:
> >   https://gitlab.com/xen-project/people/dmukhin/xen/-/tree/vuart-framework?ref_type=heads
> >
> > Specifically,
> >  https://gitlab.com/xen-project/people/dmukhin/xen/-/commit/17f44d23c1904374963c4ec839bc8219041b5d26
> >
> > enables the use of emulation_flags on Arm.
> >
> > I can move this patch to the upcoming series, if needed, but looks like it is
> > OK to have it for Arm even now.
> 
> Prior to that series making it to a ready-to-be-committed state, it'll be
> (effectively) dead code on Arm. Which strictly speaking Misra objects to.
> I wonder if you, Stefano, considered that when giving your R-b.
> 
> Further - what about PPC and RISC-V?

I have no problem plumbing this patch to the follow on series.
Will re-adjust.

> 
> Jan
>
Re: [PATCH v5 1/2] xen/domain: introduce common hardware emulation flags
Posted by Stefano Stabellini 4 months, 3 weeks ago 
On Thu, 5 Jun 2025, Jan Beulich wrote:
> On 05.06.2025 03:17, dmkhn@proton.me wrote:
> > On Wed, Jun 04, 2025 at 12:36:17PM +0200, Jan Beulich wrote:
> >> On 02.06.2025 21:17, dmkhn@proton.me wrote:
> >>> From: Denis Mukhin <dmukhin@ford.com>
> >>>
> >>> Add common emulation_flags for configuring domain emulation features.
> >>>
> >>> Print d->emulation_flags from 'q' keyhandler for better traceability while
> >>> debugging.
> >>>
> >>> Signed-off-by: Denis Mukhin <dmukhin@ford.com>
> >>> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
> >>
> >> It's not becoming clear why this would want doing, nor in how far some of
> >> the bits there may gain "common" meaning, too. Imo this kind of change is
> >> meaningful only in a series where later the common-ness is also used.
> > 
> > I have a set of upcoming changes here:
> >   https://gitlab.com/xen-project/people/dmukhin/xen/-/tree/vuart-framework?ref_type=heads
> > 
> > Specifically,
> >  https://gitlab.com/xen-project/people/dmukhin/xen/-/commit/17f44d23c1904374963c4ec839bc8219041b5d26
> > 
> > enables the use of emulation_flags on Arm.
> > 
> > I can move this patch to the upcoming series, if needed, but looks like it is
> > OK to have it for Arm even now.
> 
> Prior to that series making it to a ready-to-be-committed state, it'll be
> (effectively) dead code on Arm. Which strictly speaking Misra objects to.
> I wonder if you, Stefano, considered that when giving your R-b.

We have not been enforcing the "no dead code" rule (R2.2) especially on
a per patch basis. In general in my view, it is better to reduce dead
code rather than increase dead code, but it is OK to do so temporarily.

Patchew 2.1-devel-b67e4c2

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