| Message ID | 1564121727-30020-1-git-send-email-wanpengli@tencent.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [RESEND] KVM: X86: Use IPI shorthands in kvm guest when support | expand |
On Fri, Jul 26, 2019 at 02:15:27PM +0800, Wanpeng Li wrote: > From: Wanpeng Li <wanpengli@tencent.com> > > IPI shorthand is supported now by linux apic/x2apic driver, switch to > IPI shorthand for all excluding self and all including self destination > shorthand in kvm guest, to avoid splitting the target mask into serveral > PV IPI hypercalls. > > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: Radim Krčmář <rkrcmar@redhat.com> > Cc: Sean Christopherson <sean.j.christopherson@intel.com> > Cc: Nadav Amit <namit@vmware.com> > Signed-off-by: Wanpeng Li <wanpengli@tencent.com> > --- > Note: rebase against tip tree's x86/apic branch > > arch/x86/kernel/kvm.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c > index b7f34fe..87b73b8 100644 > --- a/arch/x86/kernel/kvm.c > +++ b/arch/x86/kernel/kvm.c > @@ -34,7 +34,9 @@ > #include <asm/hypervisor.h> > #include <asm/tlb.h> > > +static struct apic orig_apic; Copying the entire struct apic to snapshot two functions is funky, explicitly capturing the two functions would be more intuitive. Tangentially related, kvm_setup_pv_ipi() can be annotated __init, which means the function snapshots can be __ro_after_init. That being said, can't we just remove kvm_send_ipi_all() and kvm_send_ipi_allbutself()? AFAICT, the variations that lead to shorthand are only used when apic_use_ipi_shorthand is true. If that isn't the case, fixing the callers in the APIC code seems like the correct thing to do. > static int kvmapf = 1; > +DECLARE_STATIC_KEY_FALSE(apic_use_ipi_shorthand); > static int __init parse_no_kvmapf(char *arg) > { > @@ -507,12 +509,18 @@ static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector) > > static void kvm_send_ipi_allbutself(int vector) > { > - kvm_send_ipi_mask_allbutself(cpu_online_mask, vector); > + if (static_branch_likely(&apic_use_ipi_shorthand)) > + orig_apic.send_IPI_allbutself(vector); > + else > + kvm_send_ipi_mask_allbutself(cpu_online_mask, vector); > } > > static void kvm_send_ipi_all(int vector) > { > - __send_ipi_mask(cpu_online_mask, vector); > + if (static_branch_likely(&apic_use_ipi_shorthand)) > + orig_apic.send_IPI_all(vector); > + else > + __send_ipi_mask(cpu_online_mask, vector); > } > > /* > @@ -520,6 +528,8 @@ static void kvm_send_ipi_all(int vector) > */ > static void kvm_setup_pv_ipi(void) > { > + orig_apic = *apic; > + > apic->send_IPI_mask = kvm_send_ipi_mask; > apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself; > apic->send_IPI_allbutself = kvm_send_ipi_allbutself; > -- > 2.7.4 >
On Tue, 30 Jul 2019 at 01:50, Sean Christopherson <sean.j.christopherson@intel.com> wrote: > > On Fri, Jul 26, 2019 at 02:15:27PM +0800, Wanpeng Li wrote: > > From: Wanpeng Li <wanpengli@tencent.com> > > > > IPI shorthand is supported now by linux apic/x2apic driver, switch to > > IPI shorthand for all excluding self and all including self destination > > shorthand in kvm guest, to avoid splitting the target mask into serveral > > PV IPI hypercalls. > > > > Cc: Thomas Gleixner <tglx@linutronix.de> > > Cc: Paolo Bonzini <pbonzini@redhat.com> > > Cc: Radim Krčmář <rkrcmar@redhat.com> > > Cc: Sean Christopherson <sean.j.christopherson@intel.com> > > Cc: Nadav Amit <namit@vmware.com> > > Signed-off-by: Wanpeng Li <wanpengli@tencent.com> > > --- > > Note: rebase against tip tree's x86/apic branch > > > > arch/x86/kernel/kvm.c | 14 ++++++++++++-- > > 1 file changed, 12 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c > > index b7f34fe..87b73b8 100644 > > --- a/arch/x86/kernel/kvm.c > > +++ b/arch/x86/kernel/kvm.c > > @@ -34,7 +34,9 @@ > > #include <asm/hypervisor.h> > > #include <asm/tlb.h> > > > > +static struct apic orig_apic; > > Copying the entire struct apic to snapshot two functions is funky, > explicitly capturing the two functions would be more intuitive. > > Tangentially related, kvm_setup_pv_ipi() can be annotated __init, > which means the function snapshots can be __ro_after_init. > > That being said, can't we just remove kvm_send_ipi_all() and > kvm_send_ipi_allbutself()? AFAICT, the variations that lead to shorthand > are only used when apic_use_ipi_shorthand is true. If that isn't the > case, fixing the callers in the APIC code seems like the correct thing to > do. The callers in the APIC codes have already done this, so I just remove the two hooks in v2. Regards, Wanpeng Li
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index b7f34fe..87b73b8 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -34,7 +34,9 @@ #include <asm/hypervisor.h> #include <asm/tlb.h> +static struct apic orig_apic; static int kvmapf = 1; +DECLARE_STATIC_KEY_FALSE(apic_use_ipi_shorthand); static int __init parse_no_kvmapf(char *arg) { @@ -507,12 +509,18 @@ static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector) static void kvm_send_ipi_allbutself(int vector) { - kvm_send_ipi_mask_allbutself(cpu_online_mask, vector); + if (static_branch_likely(&apic_use_ipi_shorthand)) + orig_apic.send_IPI_allbutself(vector); + else + kvm_send_ipi_mask_allbutself(cpu_online_mask, vector); } static void kvm_send_ipi_all(int vector) { - __send_ipi_mask(cpu_online_mask, vector); + if (static_branch_likely(&apic_use_ipi_shorthand)) + orig_apic.send_IPI_all(vector); + else + __send_ipi_mask(cpu_online_mask, vector); } /* @@ -520,6 +528,8 @@ static void kvm_send_ipi_all(int vector) */ static void kvm_setup_pv_ipi(void) { + orig_apic = *apic; + apic->send_IPI_mask = kvm_send_ipi_mask; apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself; apic->send_IPI_allbutself = kvm_send_ipi_allbutself;