| Message ID | 20220622213656.81546-4-peterx@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | kvm/mm: Allow GUP to respond to non fatal signals | expand |
On Wed, Jun 22, 2022, Peter Xu wrote: > Add one new PFN error type to show when we cannot finish fetching the PFN > due to interruptions. For example, by receiving a generic signal. > > This prepares KVM to be able to respond to SIGUSR1 (for QEMU that's the > SIGIPI) even during e.g. handling an userfaultfd page fault. > > Signed-off-by: Peter Xu <peterx@redhat.com> > --- > include/linux/kvm_host.h | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index b646b6fcaec6..4f84a442f67f 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -96,6 +96,7 @@ > #define KVM_PFN_ERR_FAULT (KVM_PFN_ERR_MASK) > #define KVM_PFN_ERR_HWPOISON (KVM_PFN_ERR_MASK + 1) > #define KVM_PFN_ERR_RO_FAULT (KVM_PFN_ERR_MASK + 2) > +#define KVM_PFN_ERR_INTR (KVM_PFN_ERR_MASK + 3) > > /* > * error pfns indicate that the gfn is in slot but faild to > @@ -106,6 +107,16 @@ static inline bool is_error_pfn(kvm_pfn_t pfn) > return !!(pfn & KVM_PFN_ERR_MASK); > } > > +/* > + * When KVM_PFN_ERR_INTR is returned, it means we're interrupted during > + * fetching the PFN (e.g. a signal might have arrived), so we may want to > + * retry at some later point and kick the userspace to handle the signal. > + */ > +static inline bool is_intr_pfn(kvm_pfn_t pfn) > +{ > + return pfn == KVM_PFN_ERR_INTR; What about is_sigpending_pfn() and KVM_PFN_ERR_SIGPENDING? "intr" is too close to a real thing KVM will encounter, and I think knowing that KVM is effectively responding to a pending signal is the most important detail for KVM developers encountering this code for this first time. E.g. from KVM_PFN_ERR_INTR alone, one might think that any interrupt during GUP will trigger this. > +} > + > /* > * error_noslot pfns indicate that the gfn can not be > * translated to pfn - it is not in slot or failed to > -- > 2.32.0 >
On Thu, Jun 23, 2022 at 02:31:47PM +0000, Sean Christopherson wrote: > On Wed, Jun 22, 2022, Peter Xu wrote: > > Add one new PFN error type to show when we cannot finish fetching the PFN > > due to interruptions. For example, by receiving a generic signal. > > > > This prepares KVM to be able to respond to SIGUSR1 (for QEMU that's the > > SIGIPI) even during e.g. handling an userfaultfd page fault. > > > > Signed-off-by: Peter Xu <peterx@redhat.com> > > --- > > include/linux/kvm_host.h | 11 +++++++++++ > > 1 file changed, 11 insertions(+) > > > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > > index b646b6fcaec6..4f84a442f67f 100644 > > --- a/include/linux/kvm_host.h > > +++ b/include/linux/kvm_host.h > > @@ -96,6 +96,7 @@ > > #define KVM_PFN_ERR_FAULT (KVM_PFN_ERR_MASK) > > #define KVM_PFN_ERR_HWPOISON (KVM_PFN_ERR_MASK + 1) > > #define KVM_PFN_ERR_RO_FAULT (KVM_PFN_ERR_MASK + 2) > > +#define KVM_PFN_ERR_INTR (KVM_PFN_ERR_MASK + 3) > > > > /* > > * error pfns indicate that the gfn is in slot but faild to > > @@ -106,6 +107,16 @@ static inline bool is_error_pfn(kvm_pfn_t pfn) > > return !!(pfn & KVM_PFN_ERR_MASK); > > } > > > > +/* > > + * When KVM_PFN_ERR_INTR is returned, it means we're interrupted during > > + * fetching the PFN (e.g. a signal might have arrived), so we may want to > > + * retry at some later point and kick the userspace to handle the signal. > > + */ > > +static inline bool is_intr_pfn(kvm_pfn_t pfn) > > +{ > > + return pfn == KVM_PFN_ERR_INTR; > > What about is_sigpending_pfn() and KVM_PFN_ERR_SIGPENDING? "intr" is too close to > a real thing KVM will encounter, and I think knowing that KVM is effectively > responding to a pending signal is the most important detail for KVM developers > encountering this code for this first time. E.g. from KVM_PFN_ERR_INTR alone, one > might think that any interrupt during GUP will trigger this. Sounds good; INTR could be too general for KVM indeed. Thanks,
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index b646b6fcaec6..4f84a442f67f 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -96,6 +96,7 @@ #define KVM_PFN_ERR_FAULT (KVM_PFN_ERR_MASK) #define KVM_PFN_ERR_HWPOISON (KVM_PFN_ERR_MASK + 1) #define KVM_PFN_ERR_RO_FAULT (KVM_PFN_ERR_MASK + 2) +#define KVM_PFN_ERR_INTR (KVM_PFN_ERR_MASK + 3) /* * error pfns indicate that the gfn is in slot but faild to @@ -106,6 +107,16 @@ static inline bool is_error_pfn(kvm_pfn_t pfn) return !!(pfn & KVM_PFN_ERR_MASK); } +/* + * When KVM_PFN_ERR_INTR is returned, it means we're interrupted during + * fetching the PFN (e.g. a signal might have arrived), so we may want to + * retry at some later point and kick the userspace to handle the signal. + */ +static inline bool is_intr_pfn(kvm_pfn_t pfn) +{ + return pfn == KVM_PFN_ERR_INTR; +} + /* * error_noslot pfns indicate that the gfn can not be * translated to pfn - it is not in slot or failed to
Add one new PFN error type to show when we cannot finish fetching the PFN due to interruptions. For example, by receiving a generic signal. This prepares KVM to be able to respond to SIGUSR1 (for QEMU that's the SIGIPI) even during e.g. handling an userfaultfd page fault. Signed-off-by: Peter Xu <peterx@redhat.com> --- include/linux/kvm_host.h | 11 +++++++++++ 1 file changed, 11 insertions(+)