ple_window is updated on every vmentry, so there is no reason to have it
read-only anymore.
ple_window* weren't writable to prevent runtime overflow races;
they are prevented by a seqlock.
Signed-off-by: Radim Krčmář <rkrc...@redhat.com>
---
arch/x86/kvm/vmx.c | 48 +++++++++++++++++++++++++++++++++++++-----------
1 file changed, 37 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f63ac5d..bd73fa1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -132,24 +132,29 @@ module_param(nested, bool, S_IRUGO);
#define KVM_VMX_DEFAULT_PLE_WINDOW_MAX \
INT_MAX / KVM_VMX_DEFAULT_PLE_WINDOW_GROW
+static struct kernel_param_ops param_ops_ple_t;
+#define param_check_ple_t(name, p) __param_check(name, p, int)
+
+static DEFINE_SEQLOCK(ple_window_seqlock);
+
static int ple_gap = KVM_VMX_DEFAULT_PLE_GAP;
module_param(ple_gap, int, S_IRUGO);
static int ple_window = KVM_VMX_DEFAULT_PLE_WINDOW;
-module_param(ple_window, int, S_IRUGO);
+module_param(ple_window, ple_t, S_IRUGO | S_IWUSR);
/* Default doubles per-vcpu window every exit. */
static int ple_window_grow = KVM_VMX_DEFAULT_PLE_WINDOW_GROW;
-module_param(ple_window_grow, int, S_IRUGO);
+module_param(ple_window_grow, ple_t, S_IRUGO | S_IWUSR);
/* Default resets per-vcpu window every exit to ple_window. */
static int ple_window_shrink = KVM_VMX_DEFAULT_PLE_WINDOW_SHRINK;
-module_param(ple_window_shrink, int, S_IRUGO);
+module_param(ple_window_shrink, int, S_IRUGO | S_IWUSR);
/* Default is to compute the maximum so we can never overflow. */
static int ple_window_actual_max = KVM_VMX_DEFAULT_PLE_WINDOW_MAX;
static int ple_window_max = KVM_VMX_DEFAULT_PLE_WINDOW_MAX;
-module_param(ple_window_max, int, S_IRUGO);
+module_param(ple_window_max, ple_t, S_IRUGO | S_IWUSR);
extern const ulong vmx_return;
@@ -5730,13 +5735,19 @@ static void modify_ple_window(struct kvm_vcpu *vcpu,
int grow)
struct vcpu_vmx *vmx = to_vmx(vcpu);
int old = vmx->ple_window;
int new;
+ unsigned seq;
- if (grow)
- new = __grow_ple_window(old)
- else
- new = __shrink_ple_window(old, ple_window_shrink, ple_window);
+ do {
+ seq = read_seqbegin(&ple_window_seqlock);
- vmx->ple_window = max(new, ple_window);
+ if (grow)
+ new = __grow_ple_window(old);
+ else
+ new = __shrink_ple_window(old, ple_window_shrink,
+ ple_window);
+
+ vmx->ple_window = max(new, ple_window);
+ } while (read_seqretry(&ple_window_seqlock, seq));
trace_kvm_ple_window(grow, vcpu->vcpu_id, vmx->ple_window, old);
}
@@ -5750,6 +5761,23 @@ static void update_ple_window_actual_max(void)
ple_window_grow, INT_MIN);
}
+static int param_set_ple_t(const char *arg, const struct kernel_param *kp)
+{
+ int ret;
+
+ write_seqlock(&ple_window_seqlock);
+ ret = param_set_int(arg, kp);
+ update_ple_window_actual_max();
+ write_sequnlock(&ple_window_seqlock);
+
+ return ret;
+}
+
+static struct kernel_param_ops param_ops_ple_t = {
+ .set = param_set_ple_t,
+ .get = param_get_int,
+};
+
/*
* Indicate a busy-waiting vcpu in spinlock. We do not enable the PAUSE
* exiting, so only get here on cpu with PAUSE-Loop-Exiting.
@@ -9153,8 +9181,6 @@ static int __init vmx_init(void)
} else
kvm_disable_tdp();
- update_ple_window_actual_max();
-
return 0;
out7:
--
2.0.4
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