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KVM: arm/arm64: vgic-v2: Save maintenance interrupt state only if required

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Next on our list of useless accesses is the maintenance interrupt
status registers (GICH_MISR, GICH_EISR{0,1}).

It is pointless to save them if we haven't asked for a maintenance
interrupt the first place, which can only happen for two reasons:
- Underflow: GICH_HCR_UIE will be set,
- EOI: GICH_LR_EOI will be set.

These conditions can be checked on the in-memory copies of the regs.
Should any of these two condition be valid, we must read GICH_MISR.
We can then check for GICH_MISR_EOI, and only when set read
GICH_EISR*.

This means that in most case, we don't have to save them at all.

Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Marc Zyngier 2016-02-09 17:01:33 +00:00
parent 59f00ff9af
commit c813bb17f2
1 changed files with 47 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

54
virt/kvm/arm/hyp/vgic-v2-sr.c
View File

@ -21,6 +21,49 @@
#include <asm/kvm_hyp.h>
static void __hyp_text save_maint_int_state(struct kvm_vcpu *vcpu,
void __iomem *base)
{
struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
int nr_lr = vcpu->arch.vgic_cpu.nr_lr;
u32 eisr0, eisr1;
int i;
bool expect_mi;
expect_mi = !!(cpu_if->vgic_hcr & GICH_HCR_UIE);
for (i = 0; i < nr_lr; i++) {
if (!(vcpu->arch.vgic_cpu.live_lrs & (1UL << i)))
continue;
expect_mi |= (!(cpu_if->vgic_lr[i] & GICH_LR_HW) &&
(cpu_if->vgic_lr[i] & GICH_LR_EOI));
}
if (expect_mi) {
cpu_if->vgic_misr = readl_relaxed(base + GICH_MISR);
if (cpu_if->vgic_misr & GICH_MISR_EOI) {
eisr0 = readl_relaxed(base + GICH_EISR0);
if (unlikely(nr_lr > 32))
eisr1 = readl_relaxed(base + GICH_EISR1);
else
eisr1 = 0;
} else {
eisr0 = eisr1 = 0;
}
} else {
cpu_if->vgic_misr = 0;
eisr0 = eisr1 = 0;
}
#ifdef CONFIG_CPU_BIG_ENDIAN
cpu_if->vgic_eisr = ((u64)eisr0 << 32) | eisr1;
#else
cpu_if->vgic_eisr = ((u64)eisr1 << 32) | eisr0;
#endif
}
/* vcpu is already in the HYP VA space */
void __hyp_text __vgic_v2_save_state(struct kvm_vcpu *vcpu)
{
@ -28,7 +71,7 @@ void __hyp_text __vgic_v2_save_state(struct kvm_vcpu *vcpu)
struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
struct vgic_dist *vgic = &kvm->arch.vgic;
void __iomem *base = kern_hyp_va(vgic->vctrl_base);
u32 eisr0, eisr1, elrsr0, elrsr1;
u32 elrsr0, elrsr1;
int i, nr_lr;
if (!base)
@ -38,26 +81,23 @@ void __hyp_text __vgic_v2_save_state(struct kvm_vcpu *vcpu)
cpu_if->vgic_vmcr = readl_relaxed(base + GICH_VMCR);
if (vcpu->arch.vgic_cpu.live_lrs) {
eisr0 = readl_relaxed(base + GICH_EISR0);
elrsr0 = readl_relaxed(base + GICH_ELRSR0);
cpu_if->vgic_misr = readl_relaxed(base + GICH_MISR);
cpu_if->vgic_apr = readl_relaxed(base + GICH_APR);
if (unlikely(nr_lr > 32)) {
eisr1 = readl_relaxed(base + GICH_EISR1);
elrsr1 = readl_relaxed(base + GICH_ELRSR1);
} else {
eisr1 = elrsr1 = 0;
elrsr1 = 0;
}
#ifdef CONFIG_CPU_BIG_ENDIAN
cpu_if->vgic_eisr = ((u64)eisr0 << 32) | eisr1;
cpu_if->vgic_elrsr = ((u64)elrsr0 << 32) | elrsr1;
#else
cpu_if->vgic_eisr = ((u64)eisr1 << 32) | eisr0;
cpu_if->vgic_elrsr = ((u64)elrsr1 << 32) | elrsr0;
#endif
save_maint_int_state(vcpu, base);
for (i = 0; i < nr_lr; i++)
if (vcpu->arch.vgic_cpu.live_lrs & (1UL << i))
cpu_if->vgic_lr[i] = readl_relaxed(base + GICH_LR0 + (i * 4));