[1/2] arm64: KVM: regmap: Mark expected switch fall-through

Message ID 20190726112705.19000-1-anders.roxell@linaro.org
State New
Headers show
Series
  • [1/2] arm64: KVM: regmap: Mark expected switch fall-through
Related show

Commit Message

Anders Roxell July 26, 2019, 11:27 a.m.
When fall-through warnings was enabled by default, commit d93512ef0f0e
("Makefile: Globally enable fall-through warning"), the following
warnings was starting to show up:

In file included from ../arch/arm64/include/asm/kvm_emulate.h:19,
                 from ../arch/arm64/kvm/regmap.c:13:
../arch/arm64/kvm/regmap.c: In function ‘vcpu_write_spsr32’:
../arch/arm64/include/asm/kvm_hyp.h:31:3: warning: this statement may fall
 through [-Wimplicit-fallthrough=]
   asm volatile(ALTERNATIVE(__msr_s(r##nvh, "%x0"), \
   ^~~
../arch/arm64/include/asm/kvm_hyp.h:46:31: note: in expansion of macro ‘write_sysreg_elx’
 #define write_sysreg_el1(v,r) write_sysreg_elx(v, r, _EL1, _EL12)
                               ^~~~~~~~~~~~~~~~
../arch/arm64/kvm/regmap.c:180:3: note: in expansion of macro ‘write_sysreg_el1’
   write_sysreg_el1(v, SYS_SPSR);
   ^~~~~~~~~~~~~~~~
../arch/arm64/kvm/regmap.c:181:2: note: here
  case KVM_SPSR_ABT:
  ^~~~
In file included from ../arch/arm64/include/asm/cputype.h:132,
                 from ../arch/arm64/include/asm/cache.h:8,
                 from ../include/linux/cache.h:6,
                 from ../include/linux/printk.h:9,
                 from ../include/linux/kernel.h:15,
                 from ../include/asm-generic/bug.h:18,
                 from ../arch/arm64/include/asm/bug.h:26,
                 from ../include/linux/bug.h:5,
                 from ../include/linux/mmdebug.h:5,
                 from ../include/linux/mm.h:9,
                 from ../arch/arm64/kvm/regmap.c:11:
../arch/arm64/include/asm/sysreg.h:837:2: warning: this statement may fall
 through [-Wimplicit-fallthrough=]
  asm volatile("msr " __stringify(r) ", %x0"  \
  ^~~
../arch/arm64/kvm/regmap.c:182:3: note: in expansion of macro ‘write_sysreg’
   write_sysreg(v, spsr_abt);
   ^~~~~~~~~~~~
../arch/arm64/kvm/regmap.c:183:2: note: here
  case KVM_SPSR_UND:
  ^~~~

Rework to add a 'break;' in the swich-case since it didn't have that.
That also made the compiler happy and didn't warn about fall-through.

Cc: stable@vger.kernel.org # v3.16+
Fixes: a892819560c4 ("KVM: arm64: Prepare to handle deferred save/restore of 32-bit registers")
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>

---
 arch/arm64/kvm/regmap.c | 5 +++++
 1 file changed, 5 insertions(+)

-- 
2.20.1

Comments

Marc Zyngier July 26, 2019, 12:30 p.m. | #1
Hi Anders,

On Fri, 26 Jul 2019 12:27:05 +0100,
Anders Roxell <anders.roxell@linaro.org> wrote:
> 

> When fall-through warnings was enabled by default, commit d93512ef0f0e

> ("Makefile: Globally enable fall-through warning"), the following

> warnings was starting to show up:

> 

> In file included from ../arch/arm64/include/asm/kvm_emulate.h:19,

>                  from ../arch/arm64/kvm/regmap.c:13:

> ../arch/arm64/kvm/regmap.c: In function ‘vcpu_write_spsr32’:

> ../arch/arm64/include/asm/kvm_hyp.h:31:3: warning: this statement may fall

>  through [-Wimplicit-fallthrough=]

>    asm volatile(ALTERNATIVE(__msr_s(r##nvh, "%x0"), \

>    ^~~

> ../arch/arm64/include/asm/kvm_hyp.h:46:31: note: in expansion of macro ‘write_sysreg_elx’

>  #define write_sysreg_el1(v,r) write_sysreg_elx(v, r, _EL1, _EL12)

>                                ^~~~~~~~~~~~~~~~

> ../arch/arm64/kvm/regmap.c:180:3: note: in expansion of macro ‘write_sysreg_el1’

>    write_sysreg_el1(v, SYS_SPSR);

>    ^~~~~~~~~~~~~~~~

> ../arch/arm64/kvm/regmap.c:181:2: note: here

>   case KVM_SPSR_ABT:

>   ^~~~

> In file included from ../arch/arm64/include/asm/cputype.h:132,

>                  from ../arch/arm64/include/asm/cache.h:8,

>                  from ../include/linux/cache.h:6,

>                  from ../include/linux/printk.h:9,

>                  from ../include/linux/kernel.h:15,

>                  from ../include/asm-generic/bug.h:18,

>                  from ../arch/arm64/include/asm/bug.h:26,

>                  from ../include/linux/bug.h:5,

>                  from ../include/linux/mmdebug.h:5,

>                  from ../include/linux/mm.h:9,

>                  from ../arch/arm64/kvm/regmap.c:11:

> ../arch/arm64/include/asm/sysreg.h:837:2: warning: this statement may fall

>  through [-Wimplicit-fallthrough=]

>   asm volatile("msr " __stringify(r) ", %x0"  \

>   ^~~

> ../arch/arm64/kvm/regmap.c:182:3: note: in expansion of macro ‘write_sysreg’

>    write_sysreg(v, spsr_abt);

>    ^~~~~~~~~~~~

> ../arch/arm64/kvm/regmap.c:183:2: note: here

>   case KVM_SPSR_UND:

>   ^~~~

> 

> Rework to add a 'break;' in the swich-case since it didn't have that.

> That also made the compiler happy and didn't warn about fall-through.

> 

> Cc: stable@vger.kernel.org # v3.16+


Erm... Are you sure about that? Here's what I have:

$ git describe --contains  a892819560c4
kvm-arm-for-v4.17~44
$ git describe --contains --match='v*' a892819560c4
v4.17-rc1~72^2~36^2~44


> Fixes: a892819560c4 ("KVM: arm64: Prepare to handle deferred save/restore of 32-bit registers")

> Signed-off-by: Anders Roxell <anders.roxell@linaro.org>

> ---

>  arch/arm64/kvm/regmap.c | 5 +++++

>  1 file changed, 5 insertions(+)

> 

> diff --git a/arch/arm64/kvm/regmap.c b/arch/arm64/kvm/regmap.c

> index 0d60e4f0af66..a900181e3867 100644

> --- a/arch/arm64/kvm/regmap.c

> +++ b/arch/arm64/kvm/regmap.c

> @@ -178,13 +178,18 @@ void vcpu_write_spsr32(struct kvm_vcpu *vcpu, unsigned long v)

>  	switch (spsr_idx) {

>  	case KVM_SPSR_SVC:

>  		write_sysreg_el1(v, SYS_SPSR);

> +		break;

>  	case KVM_SPSR_ABT:

>  		write_sysreg(v, spsr_abt);

> +		break;

>  	case KVM_SPSR_UND:

>  		write_sysreg(v, spsr_und);

> +		break;

>  	case KVM_SPSR_IRQ:

>  		write_sysreg(v, spsr_irq);

> +		break;

>  	case KVM_SPSR_FIQ:

>  		write_sysreg(v, spsr_fiq);

> +		break;

>  	}

>  }


Otherwise looks like the right fix to me. Let me know what you think
about the Fixes: tag (no need to resend for that).

Thanks,

	M.

-- 
Jazz is not dead, it just smells funny.
Anders Roxell July 26, 2019, 2:05 p.m. | #2
On Fri, 26 Jul 2019 at 14:30, Marc Zyngier <marc.zyngier@arm.com> wrote:
>

> Hi Anders,

>

> On Fri, 26 Jul 2019 12:27:05 +0100,

> Anders Roxell <anders.roxell@linaro.org> wrote:

> >

> > When fall-through warnings was enabled by default, commit d93512ef0f0e

> > ("Makefile: Globally enable fall-through warning"), the following

> > warnings was starting to show up:

> >

> > In file included from ../arch/arm64/include/asm/kvm_emulate.h:19,

> >                  from ../arch/arm64/kvm/regmap.c:13:

> > ../arch/arm64/kvm/regmap.c: In function ‘vcpu_write_spsr32’:

> > ../arch/arm64/include/asm/kvm_hyp.h:31:3: warning: this statement may fall

> >  through [-Wimplicit-fallthrough=]

> >    asm volatile(ALTERNATIVE(__msr_s(r##nvh, "%x0"), \

> >    ^~~

> > ../arch/arm64/include/asm/kvm_hyp.h:46:31: note: in expansion of macro ‘write_sysreg_elx’

> >  #define write_sysreg_el1(v,r) write_sysreg_elx(v, r, _EL1, _EL12)

> >                                ^~~~~~~~~~~~~~~~

> > ../arch/arm64/kvm/regmap.c:180:3: note: in expansion of macro ‘write_sysreg_el1’

> >    write_sysreg_el1(v, SYS_SPSR);

> >    ^~~~~~~~~~~~~~~~

> > ../arch/arm64/kvm/regmap.c:181:2: note: here

> >   case KVM_SPSR_ABT:

> >   ^~~~

> > In file included from ../arch/arm64/include/asm/cputype.h:132,

> >                  from ../arch/arm64/include/asm/cache.h:8,

> >                  from ../include/linux/cache.h:6,

> >                  from ../include/linux/printk.h:9,

> >                  from ../include/linux/kernel.h:15,

> >                  from ../include/asm-generic/bug.h:18,

> >                  from ../arch/arm64/include/asm/bug.h:26,

> >                  from ../include/linux/bug.h:5,

> >                  from ../include/linux/mmdebug.h:5,

> >                  from ../include/linux/mm.h:9,

> >                  from ../arch/arm64/kvm/regmap.c:11:

> > ../arch/arm64/include/asm/sysreg.h:837:2: warning: this statement may fall

> >  through [-Wimplicit-fallthrough=]

> >   asm volatile("msr " __stringify(r) ", %x0"  \

> >   ^~~

> > ../arch/arm64/kvm/regmap.c:182:3: note: in expansion of macro ‘write_sysreg’

> >    write_sysreg(v, spsr_abt);

> >    ^~~~~~~~~~~~

> > ../arch/arm64/kvm/regmap.c:183:2: note: here

> >   case KVM_SPSR_UND:

> >   ^~~~

> >

> > Rework to add a 'break;' in the swich-case since it didn't have that.

> > That also made the compiler happy and didn't warn about fall-through.

> >

> > Cc: stable@vger.kernel.org # v3.16+

>

> Erm... Are you sure about that?


I made two mistakes.
1. saying 3.x instead of 4.x
2. I said the same kernel that 'git describe' showed and not the later one.

I did not know about '--match='.

> Here's what I have:

>

> $ git describe --contains  a892819560c4

> kvm-arm-for-v4.17~44

> $ git describe --contains --match='v*' a892819560c4

> v4.17-rc1~72^2~36^2~44


That's correct.

>

>

> > Fixes: a892819560c4 ("KVM: arm64: Prepare to handle deferred save/restore of 32-bit registers")

> > Signed-off-by: Anders Roxell <anders.roxell@linaro.org>

> > ---

> >  arch/arm64/kvm/regmap.c | 5 +++++

> >  1 file changed, 5 insertions(+)

> >

> > diff --git a/arch/arm64/kvm/regmap.c b/arch/arm64/kvm/regmap.c

> > index 0d60e4f0af66..a900181e3867 100644

> > --- a/arch/arm64/kvm/regmap.c

> > +++ b/arch/arm64/kvm/regmap.c

> > @@ -178,13 +178,18 @@ void vcpu_write_spsr32(struct kvm_vcpu *vcpu, unsigned long v)

> >       switch (spsr_idx) {

> >       case KVM_SPSR_SVC:

> >               write_sysreg_el1(v, SYS_SPSR);

> > +             break;

> >       case KVM_SPSR_ABT:

> >               write_sysreg(v, spsr_abt);

> > +             break;

> >       case KVM_SPSR_UND:

> >               write_sysreg(v, spsr_und);

> > +             break;

> >       case KVM_SPSR_IRQ:

> >               write_sysreg(v, spsr_irq);

> > +             break;

> >       case KVM_SPSR_FIQ:

> >               write_sysreg(v, spsr_fiq);

> > +             break;

> >       }

> >  }

>

> Otherwise looks like the right fix to me. Let me know what you think

> about the Fixes: tag (no need to resend for that).


It should be v4.17+.

Cheers,
Anders

Patch

diff --git a/arch/arm64/kvm/regmap.c b/arch/arm64/kvm/regmap.c
index 0d60e4f0af66..a900181e3867 100644
--- a/arch/arm64/kvm/regmap.c
+++ b/arch/arm64/kvm/regmap.c
@@ -178,13 +178,18 @@  void vcpu_write_spsr32(struct kvm_vcpu *vcpu, unsigned long v)
 	switch (spsr_idx) {
 	case KVM_SPSR_SVC:
 		write_sysreg_el1(v, SYS_SPSR);
+		break;
 	case KVM_SPSR_ABT:
 		write_sysreg(v, spsr_abt);
+		break;
 	case KVM_SPSR_UND:
 		write_sysreg(v, spsr_und);
+		break;
 	case KVM_SPSR_IRQ:
 		write_sysreg(v, spsr_irq);
+		break;
 	case KVM_SPSR_FIQ:
 		write_sysreg(v, spsr_fiq);
+		break;
 	}
 }