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KVM: arm64: nv: Accelerate EL0 timer read accesses when FEAT_ECV in use

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Although FEAT_ECV allows us to correctly emulate the timers, it also
reduces performances pretty badly.

Mitigate this by emulating the CTL/CVAL register reads in the
inner run loop, without returning to the general kernel.

Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20241217142321.763801-6-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier
2024-12-17 14:23:13 +00:00
parent 2cd2a77f9c
commit 338f8ea519
4 changed files with 122 additions and 18 deletions
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21
arch/arm64/kvm/arch_timer.c
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@@ -101,21 +101,6 @@ u64 timer_get_cval(struct arch_timer_context *ctxt)
}
}
static u64 timer_get_offset(struct arch_timer_context *ctxt)
{
u64 offset = 0;
if (!ctxt)
return 0;
if (ctxt->offset.vm_offset)
offset += *ctxt->offset.vm_offset;
if (ctxt->offset.vcpu_offset)
offset += *ctxt->offset.vcpu_offset;
return offset;
}
static void timer_set_ctl(struct arch_timer_context *ctxt, u32 ctl)
{
struct kvm_vcpu *vcpu = ctxt->vcpu;
@@ -964,10 +949,10 @@ void kvm_timer_sync_nested(struct kvm_vcpu *vcpu)
* which allows trapping of the timer registers even with NV2.
* Still, this is still worse than FEAT_NV on its own. Meh.
*/
if (cpus_have_final_cap(ARM64_HAS_ECV) || !is_hyp_ctxt(vcpu))
return;
if (!vcpu_el2_e2h_is_set(vcpu)) {
if (cpus_have_final_cap(ARM64_HAS_ECV))
return;
/*
* A non-VHE guest hypervisor doesn't have any direct access
* to its timers: the EL2 registers trap (and the HW is