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KVM: PPC: Book3S HV: Don't use existing "prodded" flag for XIVE escalations 

The prodded flag is only cleared at the beginning of H_CEDE,
so every time we have an escalation, we will cause the *next*
H_CEDE to return immediately.

Instead use a dedicated "irq_pending" flag to indicate that
a guest interrupt is pending for the VCPU. We don't reuse the
existing exception bitmap so as to avoid expensive atomic ops.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This commit is contained in:
Benjamin Herrenschmidt 2018-01-12 13:37:13 +11:00 committed by Paul Mackerras
parent bf4159da47
commit 2267ea7661
5 changed files with 14 additions and 3 deletions
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1
arch/powerpc/include/asm/kvm_host.h
View File

@ -709,6 +709,7 @@ struct kvm_vcpu_arch {
u8 ceded;
u8 prodded;
u8 doorbell_request;
u8 irq_pending; /* Used by XIVE to signal pending guest irqs */
u32 last_inst;
struct swait_queue_head *wqp;

1
arch/powerpc/kernel/asm-offsets.c
View File

@ -514,6 +514,7 @@ int main(void)
OFFSET(VCPU_PENDING_EXC, kvm_vcpu, arch.pending_exceptions);
OFFSET(VCPU_CEDED, kvm_vcpu, arch.ceded);
OFFSET(VCPU_PRODDED, kvm_vcpu, arch.prodded);
OFFSET(VCPU_IRQ_PENDING, kvm_vcpu, arch.irq_pending);
OFFSET(VCPU_DBELL_REQ, kvm_vcpu, arch.doorbell_request);
OFFSET(VCPU_MMCR, kvm_vcpu, arch.mmcr);
OFFSET(VCPU_PMC, kvm_vcpu, arch.pmc);

2
arch/powerpc/kvm/book3s_hv.c
View File

@ -2999,7 +2999,7 @@ static inline bool xive_interrupt_pending(struct kvm_vcpu *vcpu)
{
if (!xive_enabled())
return false;
return vcpu->arch.xive_saved_state.pipr <
return vcpu->arch.irq_pending || vcpu->arch.xive_saved_state.pipr <
vcpu->arch.xive_saved_state.cppr;
}
#else

10
arch/powerpc/kvm/book3s_hv_rmhandlers.S
View File

@ -1035,6 +1035,16 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300)
li r9, 1
stw r9, VCPU_XIVE_PUSHED(r4)
eieio
/*
* We clear the irq_pending flag. There is a small chance of a
* race vs. the escalation interrupt happening on another
* processor setting it again, but the only consequence is to
* cause a spurrious wakeup on the next H_CEDE which is not an
* issue.
*/
li r0,0
stb r0, VCPU_IRQ_PENDING(r4)
no_xive:
#endif /* CONFIG_KVM_XICS */

3
arch/powerpc/kvm/book3s_xive.c
View File

@ -84,8 +84,7 @@ static irqreturn_t xive_esc_irq(int irq, void *data)
{
struct kvm_vcpu *vcpu = data;
/* We use the existing H_PROD mechanism to wake up the target */
vcpu->arch.prodded = 1;
vcpu->arch.irq_pending = 1;
smp_mb();
if (vcpu->arch.ceded)
kvmppc_fast_vcpu_kick(vcpu);