Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Wed, Jun 20, 2018 at 10:02:15AM +0200, Paolo Bonzini wrote: > On 20/06/2018 01:45, Matthias Kaehlcke wrote: > > > > v4.16 with an x86 allyesconfig and a few drivers disabled since they > > don't build with clang (yet): > > > > 16 occurrences of -Wconstant-conversion, including the ones fixed

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Wed, Jun 20, 2018 at 10:02:15AM +0200, Paolo Bonzini wrote: > On 20/06/2018 01:45, Matthias Kaehlcke wrote: > > > > v4.16 with an x86 allyesconfig and a few drivers disabled since they > > don't build with clang (yet): > > > > 16 occurrences of -Wconstant-conversion, including the ones fixed

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On 20/06/2018 01:45, Matthias Kaehlcke wrote: > > v4.16 with an x86 allyesconfig and a few drivers disabled since they > don't build with clang (yet): > > 16 occurrences of -Wconstant-conversion, including the ones fixed by > this patch. Certainly no need for an endless churn of patches, and >

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On 20/06/2018 01:45, Matthias Kaehlcke wrote: > > v4.16 with an x86 allyesconfig and a few drivers disabled since they > don't build with clang (yet): > > 16 occurrences of -Wconstant-conversion, including the ones fixed by > this patch. Certainly no need for an endless churn of patches, and >

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, Jun 19, 2018 at 05:18:02PM -0700, Joe Perches wrote: > On Tue, 2018-06-19 at 16:45 -0700, Matthias Kaehlcke wrote: > > On Tue, Jun 19, 2018 at 02:55:05PM -0700, Joe Perches wrote: > > > Well, you advocate to disable a possibly useful warning globally ... > > > You're advocating for making

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, Jun 19, 2018 at 05:18:02PM -0700, Joe Perches wrote: > On Tue, 2018-06-19 at 16:45 -0700, Matthias Kaehlcke wrote: > > On Tue, Jun 19, 2018 at 02:55:05PM -0700, Joe Perches wrote: > > > Well, you advocate to disable a possibly useful warning globally ... > > > You're advocating for making

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, 2018-06-19 at 16:45 -0700, Matthias Kaehlcke wrote: > On Tue, Jun 19, 2018 at 02:55:05PM -0700, Joe Perches wrote: > > Well, you advocate to disable a possibly useful warning globally ... > > You're advocating for making the code more complex/ugly for a > > condition where the result is

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, 2018-06-19 at 16:45 -0700, Matthias Kaehlcke wrote: > On Tue, Jun 19, 2018 at 02:55:05PM -0700, Joe Perches wrote: > > Well, you advocate to disable a possibly useful warning globally ... > > You're advocating for making the code more complex/ugly for a > > condition where the result is

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, Jun 19, 2018 at 02:55:05PM -0700, Joe Perches wrote: > On Tue, 2018-06-19 at 14:10 -0700, Matthias Kaehlcke wrote: > > On Tue, Jun 19, 2018 at 12:11:27PM -0700, Joe Perches wrote: > > > -Wconstant-conversion is only issued when a *constant value* is assigned > > > to > > an incompatible

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, Jun 19, 2018 at 02:55:05PM -0700, Joe Perches wrote: > On Tue, 2018-06-19 at 14:10 -0700, Matthias Kaehlcke wrote: > > On Tue, Jun 19, 2018 at 12:11:27PM -0700, Joe Perches wrote: > > > -Wconstant-conversion is only issued when a *constant value* is assigned > > > to > > an incompatible

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, 2018-06-19 at 14:10 -0700, Matthias Kaehlcke wrote: > On Tue, Jun 19, 2018 at 12:11:27PM -0700, Joe Perches wrote: > > -Wconstant-conversion is only issued when a *constant value* is assigned to > an incompatible type. > > > Trying to allow a "make W=3" to be compiler warning message free

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, 2018-06-19 at 14:10 -0700, Matthias Kaehlcke wrote: > On Tue, Jun 19, 2018 at 12:11:27PM -0700, Joe Perches wrote: > > -Wconstant-conversion is only issued when a *constant value* is assigned to > an incompatible type. > > > Trying to allow a "make W=3" to be compiler warning message free

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, Jun 19, 2018 at 12:11:27PM -0700, Joe Perches wrote: > On Tue, 2018-06-19 at 11:36 -0700, Matthias Kaehlcke wrote: > > On Tue, Jun 19, 2018 at 11:07:47AM -0700, Joe Perches wrote: > > > On Tue, 2018-06-19 at 19:35 +0200, Paolo Bonzini wrote: > > > > On 19/06/2018 19:23, Joe Perches wrote:

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, Jun 19, 2018 at 12:11:27PM -0700, Joe Perches wrote: > On Tue, 2018-06-19 at 11:36 -0700, Matthias Kaehlcke wrote: > > On Tue, Jun 19, 2018 at 11:07:47AM -0700, Joe Perches wrote: > > > On Tue, 2018-06-19 at 19:35 +0200, Paolo Bonzini wrote: > > > > On 19/06/2018 19:23, Joe Perches wrote:

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, 2018-06-19 at 11:36 -0700, Matthias Kaehlcke wrote: > On Tue, Jun 19, 2018 at 11:07:47AM -0700, Joe Perches wrote: > > On Tue, 2018-06-19 at 19:35 +0200, Paolo Bonzini wrote: > > > On 19/06/2018 19:23, Joe Perches wrote: > > > > On Tue, 2018-06-19 at 10:08 -0700, Nick Desaulniers wrote: >

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, 2018-06-19 at 11:36 -0700, Matthias Kaehlcke wrote: > On Tue, Jun 19, 2018 at 11:07:47AM -0700, Joe Perches wrote: > > On Tue, 2018-06-19 at 19:35 +0200, Paolo Bonzini wrote: > > > On 19/06/2018 19:23, Joe Perches wrote: > > > > On Tue, 2018-06-19 at 10:08 -0700, Nick Desaulniers wrote: >

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, Jun 19, 2018 at 07:13:41PM +0200, Paolo Bonzini wrote: > On 19/06/2018 19:08, Nick Desaulniers wrote: > >> This one really makes the code uglier though, so I'm not really inclined > >> to applying the patch. > > Note that of the three variables (w, u, x), only u is used later on. > > What

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, Jun 19, 2018 at 07:13:41PM +0200, Paolo Bonzini wrote: > On 19/06/2018 19:08, Nick Desaulniers wrote: > >> This one really makes the code uglier though, so I'm not really inclined > >> to applying the patch. > > Note that of the three variables (w, u, x), only u is used later on. > > What

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, Jun 19, 2018 at 11:07:47AM -0700, Joe Perches wrote: > On Tue, 2018-06-19 at 19:35 +0200, Paolo Bonzini wrote: > > On 19/06/2018 19:23, Joe Perches wrote: > > > On Tue, 2018-06-19 at 10:08 -0700, Nick Desaulniers wrote: > > > > On Tue, Jun 19, 2018 at 8:19 AM Paolo Bonzini > > > > wrote:

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, Jun 19, 2018 at 11:07:47AM -0700, Joe Perches wrote: > On Tue, 2018-06-19 at 19:35 +0200, Paolo Bonzini wrote: > > On 19/06/2018 19:23, Joe Perches wrote: > > > On Tue, 2018-06-19 at 10:08 -0700, Nick Desaulniers wrote: > > > > On Tue, Jun 19, 2018 at 8:19 AM Paolo Bonzini > > > > wrote:

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, 2018-06-19 at 19:35 +0200, Paolo Bonzini wrote: > On 19/06/2018 19:23, Joe Perches wrote: > > On Tue, 2018-06-19 at 10:08 -0700, Nick Desaulniers wrote: > > > On Tue, Jun 19, 2018 at 8:19 AM Paolo Bonzini wrote: > > > > > > > > On 15/06/2018 20:45, Nick Desaulniers wrote: > > > > > > >

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, 2018-06-19 at 19:35 +0200, Paolo Bonzini wrote: > On 19/06/2018 19:23, Joe Perches wrote: > > On Tue, 2018-06-19 at 10:08 -0700, Nick Desaulniers wrote: > > > On Tue, Jun 19, 2018 at 8:19 AM Paolo Bonzini wrote: > > > > > > > > On 15/06/2018 20:45, Nick Desaulniers wrote: > > > > > > >

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On 19/06/2018 19:23, Joe Perches wrote: > On Tue, 2018-06-19 at 10:08 -0700, Nick Desaulniers wrote: >> On Tue, Jun 19, 2018 at 8:19 AM Paolo Bonzini wrote: >>> >>> On 15/06/2018 20:45, Nick Desaulniers wrote: > >> In any case I think it it preferable to fix the code over disabling >>

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On 19/06/2018 19:23, Joe Perches wrote: > On Tue, 2018-06-19 at 10:08 -0700, Nick Desaulniers wrote: >> On Tue, Jun 19, 2018 at 8:19 AM Paolo Bonzini wrote: >>> >>> On 15/06/2018 20:45, Nick Desaulniers wrote: > >> In any case I think it it preferable to fix the code over disabling >>

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, 2018-06-19 at 10:08 -0700, Nick Desaulniers wrote: > On Tue, Jun 19, 2018 at 8:19 AM Paolo Bonzini wrote: > > > > On 15/06/2018 20:45, Nick Desaulniers wrote: > > > > > > > > > In any case I think it it preferable to fix the code over disabling > > > > > the warning, unless the warning

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, 2018-06-19 at 10:08 -0700, Nick Desaulniers wrote: > On Tue, Jun 19, 2018 at 8:19 AM Paolo Bonzini wrote: > > > > On 15/06/2018 20:45, Nick Desaulniers wrote: > > > > > > > > > In any case I think it it preferable to fix the code over disabling > > > > > the warning, unless the warning

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On 19/06/2018 19:08, Nick Desaulniers wrote: >> This one really makes the code uglier though, so I'm not really inclined >> to applying the patch. > Note that of the three variables (w, u, x), only u is used later on. > What about declaring them as negated with the cast, that way there's > no cast

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On 19/06/2018 19:08, Nick Desaulniers wrote: >> This one really makes the code uglier though, so I'm not really inclined >> to applying the patch. > Note that of the three variables (w, u, x), only u is used later on. > What about declaring them as negated with the cast, that way there's > no cast

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, Jun 19, 2018 at 8:19 AM Paolo Bonzini wrote: > > On 15/06/2018 20:45, Nick Desaulniers wrote: > >> > >>> In any case I think it it preferable to fix the code over disabling > >>> the warning, unless the warning is bogus or there are just too many > >>> occurrences. > >> Maybe. > >

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Tue, Jun 19, 2018 at 8:19 AM Paolo Bonzini wrote: > > On 15/06/2018 20:45, Nick Desaulniers wrote: > >> > >>> In any case I think it it preferable to fix the code over disabling > >>> the warning, unless the warning is bogus or there are just too many > >>> occurrences. > >> Maybe. > >

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On 15/06/2018 20:45, Nick Desaulniers wrote: >> >>> In any case I think it it preferable to fix the code over disabling >>> the warning, unless the warning is bogus or there are just too many >>> occurrences. >> Maybe. > Spurious warning today, actual bug tomorrow? I prefer to not to > disable

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On 15/06/2018 20:45, Nick Desaulniers wrote: >> >>> In any case I think it it preferable to fix the code over disabling >>> the warning, unless the warning is bogus or there are just too many >>> occurrences. >> Maybe. > Spurious warning today, actual bug tomorrow? I prefer to not to > disable

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

Hi Matthias, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on kvm/linux-next] [also build test WARNING on v4.17 next-20180615] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url:

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

Hi Matthias, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on kvm/linux-next] [also build test WARNING on v4.17 next-20180615] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url:

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Fri, Jun 15, 2018 at 11:40 AM Joe Perches wrote: > > On Fri, 2018-06-15 at 11:29 -0700, Matthias Kaehlcke wrote: > > On Fri, Jun 15, 2018 at 11:18:12AM -0700, Joe Perches wrote: > > > On Fri, 2018-06-15 at 11:04 -0700, Nick Desaulniers wrote: > > > > On Fri, Jun 15, 2018 at 10:47 AM Matthias

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Fri, Jun 15, 2018 at 11:40 AM Joe Perches wrote: > > On Fri, 2018-06-15 at 11:29 -0700, Matthias Kaehlcke wrote: > > On Fri, Jun 15, 2018 at 11:18:12AM -0700, Joe Perches wrote: > > > On Fri, 2018-06-15 at 11:04 -0700, Nick Desaulniers wrote: > > > > On Fri, Jun 15, 2018 at 10:47 AM Matthias

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Fri, 2018-06-15 at 11:29 -0700, Matthias Kaehlcke wrote: > On Fri, Jun 15, 2018 at 11:18:12AM -0700, Joe Perches wrote: > > On Fri, 2018-06-15 at 11:04 -0700, Nick Desaulniers wrote: > > > On Fri, Jun 15, 2018 at 10:47 AM Matthias Kaehlcke > > > wrote: > > > > > > > >

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Fri, 2018-06-15 at 11:29 -0700, Matthias Kaehlcke wrote: > On Fri, Jun 15, 2018 at 11:18:12AM -0700, Joe Perches wrote: > > On Fri, 2018-06-15 at 11:04 -0700, Nick Desaulniers wrote: > > > On Fri, Jun 15, 2018 at 10:47 AM Matthias Kaehlcke > > > wrote: > > > > > > > >

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Fri, Jun 15, 2018 at 11:18:12AM -0700, Joe Perches wrote: > On Fri, 2018-06-15 at 11:04 -0700, Nick Desaulniers wrote: > > On Fri, Jun 15, 2018 at 10:47 AM Matthias Kaehlcke > > wrote: > > > > > > update_permission_bitmask() negates u8 bitmask values and assigns them > > > to variables of

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Fri, Jun 15, 2018 at 11:18:12AM -0700, Joe Perches wrote: > On Fri, 2018-06-15 at 11:04 -0700, Nick Desaulniers wrote: > > On Fri, Jun 15, 2018 at 10:47 AM Matthias Kaehlcke > > wrote: > > > > > > update_permission_bitmask() negates u8 bitmask values and assigns them > > > to variables of

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Fri, 2018-06-15 at 11:04 -0700, Nick Desaulniers wrote: > On Fri, Jun 15, 2018 at 10:47 AM Matthias Kaehlcke wrote: > > > > update_permission_bitmask() negates u8 bitmask values and assigns them > > to variables of type u8. Since the MSB is set in the bitmask values the > > compiler expands

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Fri, 2018-06-15 at 11:04 -0700, Nick Desaulniers wrote: > On Fri, Jun 15, 2018 at 10:47 AM Matthias Kaehlcke wrote: > > > > update_permission_bitmask() negates u8 bitmask values and assigns them > > to variables of type u8. Since the MSB is set in the bitmask values the > > compiler expands

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Fri, Jun 15, 2018 at 10:47 AM Matthias Kaehlcke wrote: > > update_permission_bitmask() negates u8 bitmask values and assigns them > to variables of type u8. Since the MSB is set in the bitmask values the > compiler expands the negated values to int, which then are assigned to > u8 variables.

Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission_bitmask()

On Fri, Jun 15, 2018 at 10:47 AM Matthias Kaehlcke wrote: > > update_permission_bitmask() negates u8 bitmask values and assigns them > to variables of type u8. Since the MSB is set in the bitmask values the > compiler expands the negated values to int, which then are assigned to > u8 variables.