From 18abdc3425aa546424672d3b1f932ecc55132368 Mon Sep 17 00:00:00 2001 From: Babu Moger Date: Fri, 16 Mar 2018 16:37:23 -0400 Subject: [PATCH] KVM: VMX: Remove ple_window_actual_max MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Get rid of ple_window_actual_max, because its benefits are really minuscule and the logic is complicated. The overflows(and underflow) are controlled in __ple_window_grow and _ple_window_shrink respectively. Suggested-by: Radim Krčmář Signed-off-by: Babu Moger [Fixed potential wraparound and change the max to UINT_MAX. - Radim] Signed-off-by: Radim Krčmář --- arch/x86/kvm/vmx.c | 31 ++++++------------------------- 1 file changed, 6 insertions(+), 25 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 4eb252b13121..7a92e2e1ea2e 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -172,8 +172,7 @@ module_param_named(preemption_timer, enable_preemption_timer, bool, S_IRUGO); #define KVM_VMX_DEFAULT_PLE_WINDOW 4096 #define KVM_VMX_DEFAULT_PLE_WINDOW_GROW 2 #define KVM_VMX_DEFAULT_PLE_WINDOW_SHRINK 0 -#define KVM_VMX_DEFAULT_PLE_WINDOW_MAX \ - INT_MAX / KVM_VMX_DEFAULT_PLE_WINDOW_GROW +#define KVM_VMX_DEFAULT_PLE_WINDOW_MAX UINT_MAX static unsigned int ple_gap = KVM_VMX_DEFAULT_PLE_GAP; module_param(ple_gap, uint, 0444); @@ -190,7 +189,6 @@ static unsigned int ple_window_shrink = KVM_VMX_DEFAULT_PLE_WINDOW_SHRINK; module_param(ple_window_shrink, uint, 0444); /* Default is to compute the maximum so we can never overflow. */ -static unsigned int ple_window_actual_max = KVM_VMX_DEFAULT_PLE_WINDOW_MAX; static unsigned int ple_window_max = KVM_VMX_DEFAULT_PLE_WINDOW_MAX; module_param(ple_window_max, uint, 0444); @@ -6986,17 +6984,17 @@ out: static unsigned int __grow_ple_window(unsigned int val) { + u64 ret = val; + if (ple_window_grow < 1) return ple_window; - val = min(val, ple_window_actual_max); - if (ple_window_grow < ple_window) - val *= ple_window_grow; + ret *= ple_window_grow; else - val += ple_window_grow; + ret += ple_window_grow; - return val; + return min(ret, (u64)ple_window_max); } static unsigned int __shrink_ple_window(unsigned int val, @@ -7040,21 +7038,6 @@ static void shrink_ple_window(struct kvm_vcpu *vcpu) trace_kvm_ple_window_shrink(vcpu->vcpu_id, vmx->ple_window, old); } -/* - * ple_window_actual_max is computed to be one grow_ple_window() below - * ple_window_max. (See __grow_ple_window for the reason.) - * This prevents overflows, because ple_window_max is int. - * ple_window_max effectively rounded down to a multiple of ple_window_grow in - * this process. - * ple_window_max is also prevented from setting vmx->ple_window < ple_window. - */ -static void update_ple_window_actual_max(void) -{ - ple_window_actual_max = - __shrink_ple_window(max(ple_window_max, ple_window), - ple_window_grow, INT_MIN); -} - /* * Handler for POSTED_INTERRUPT_WAKEUP_VECTOR. */ @@ -7175,8 +7158,6 @@ static __init int hardware_setup(void) else kvm_disable_tdp(); - update_ple_window_actual_max(); - /* * Only enable PML when hardware supports PML feature, and both EPT * and EPT A/D bit features are enabled -- PML depends on them to work. -- 2.30.2