[RFC v2 PATCH 19/21] KVM: Enable direct EOI for directly routed interrupts to guests

Tomoki Sekiyama
2012-09-06T11:28:59Z

Enable direct access to EOI MSR of x2apic to accelerate guests.
This accelerate handling of interrupts delivered directly to guest from
passed-through PCI devices. When a virtual IRQ is injected, this feature
is disabled in order to route following EOI to virtual APIC. Then, it is
enabled again after every virtual IRQ is handled.

Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
---

arch/x86/kvm/vmx.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++--
1 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 39a4cb4..f93e08c 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -636,6 +636,10 @@ static unsigned long *vmx_io_bitmap_a;
static unsigned long *vmx_io_bitmap_b;
static unsigned long *vmx_msr_bitmap_legacy;
static unsigned long *vmx_msr_bitmap_longmode;
+#ifdef CONFIG_SLAVE_CPU
+static unsigned long *vmx_msr_bitmap_slave_legacy;
+static unsigned long *vmx_msr_bitmap_slave_longmode;
+#endif

static bool cpu_has_load_ia32_efer;
static bool cpu_has_load_perf_global_ctrl;
@@ -912,6 +916,11 @@ static void nested_vmx_entry_failure(struct kvm_vcpu *vcpu,
struct vmcs12 *vmcs12,
u32 reason, unsigned long qualification);

+static void vmx_disable_intercept_for_msr(u32 msr, bool longmode_only);
+#ifdef CONFIG_SLAVE_CPU
+static void vmx_disable_intercept_for_msr_slave(u32 msr, bool longmode_only);
+#endif
+
static int __find_msr_index(struct vcpu_vmx *vmx, u32 msr)
{
int i;
@@ -1716,13 +1725,28 @@ static void vmx_set_direct_interrupt(struct kvm_vcpu *vcpu, bool enabled)
#ifdef CONFIG_SLAVE_CPU
void *msr_bitmap;

- if (enabled)
+ if (enabled) {
vmcs_clear_bits(PIN_BASED_VM_EXEC_CONTROL,
PIN_BASED_EXT_INTR_MASK);
- else
+
+ if (cpu_has_vmx_msr_bitmap()) {
+ msr_bitmap = is_long_mode(vcpu) ?
+ vmx_msr_bitmap_slave_longmode :
+ vmx_msr_bitmap_slave_legacy;
+ vmcs_write64(MSR_BITMAP, __pa(msr_bitmap));
+ }
+ } else {
vmcs_set_bits(PIN_BASED_VM_EXEC_CONTROL,
PIN_BASED_EXT_INTR_MASK);

+ if (cpu_has_vmx_msr_bitmap()) {
+ msr_bitmap = is_long_mode(vcpu) ?
+ vmx_msr_bitmap_longmode :
+ vmx_msr_bitmap_legacy;
+ vmcs_write64(MSR_BITMAP, __pa(msr_bitmap));
+ }
+ }
+
trace_kvm_set_direct_interrupt(vcpu, enabled);
#endif
}
@@ -3771,6 +3795,16 @@ static void vmx_disable_intercept_for_msr(u32 msr, bool longmode_only)
__vmx_disable_intercept_for_msr(vmx_msr_bitmap_longmode, msr);
}

+#ifdef CONFIG_SLAVE_CPU
+static void vmx_disable_intercept_for_msr_slave(u32 msr, bool longmode_only)
+{
+ if (!longmode_only)
+ __vmx_disable_intercept_for_msr(vmx_msr_bitmap_slave_legacy,
+ msr);
+ __vmx_disable_intercept_for_msr(vmx_msr_bitmap_slave_longmode, msr);
+}
+#endif
+
/*
* Set up the vmcs's constant host-state fields, i.e., host-state fields that
* will not change in the lifetime of the guest.
@@ -7474,6 +7508,22 @@ static int __init vmx_init(void)
goto out2;

+#ifdef CONFIG_SLAVE_CPU
+ vmx_msr_bitmap_slave_legacy =
+ (unsigned long *)__get_free_page(GFP_KERNEL);
+ if (!vmx_msr_bitmap_slave_legacy) {
+ r = -ENOMEM;
+ goto out1s;
+ }
+
+ vmx_msr_bitmap_slave_longmode =
+ (unsigned long *)__get_free_page(GFP_KERNEL);
+ if (!vmx_msr_bitmap_slave_longmode) {
+ r = -ENOMEM;
+ goto out2s;
+ }
+#endif
+
/*
* Allow direct access to the PC debug port (it is often used for I/O
* delays, but the vmexits simply slow things down).
@@ -7500,6 +7550,15 @@ static int __init vmx_init(void)
vmx_disable_intercept_for_msr(MSR_IA32_SYSENTER_ESP, false);
vmx_disable_intercept_for_msr(MSR_IA32_SYSENTER_EIP, false);

+#ifdef CONFIG_SLAVE_CPU
+ memcpy(vmx_msr_bitmap_slave_legacy,
+ vmx_msr_bitmap_legacy, PAGE_SIZE);
+ memcpy(vmx_msr_bitmap_slave_longmode,
+ vmx_msr_bitmap_longmode, PAGE_SIZE);
+ vmx_disable_intercept_for_msr_slave(
+ APIC_BASE_MSR + (APIC_EOI >> 4), false);
+#endif
+
if (enable_ept) {
kvm_mmu_set_mask_ptes(0ull,
(enable_ept_ad_bits) ? VMX_EPT_ACCESS_BIT : 0ull,
@@ -7513,6 +7572,12 @@ static int __init vmx_init(void)
return 0;

out3:
+#ifdef CONFIG_SLAVE_CPU
+ free_page((unsigned long)vmx_msr_bitmap_slave_longmode);
+out2s:
+ free_page((unsigned long)vmx_msr_bitmap_slave_legacy);
+out1s:
+#endif
free_page((unsigned long)vmx_msr_bitmap_longmode);
out2:
free_page((unsigned long)vmx_msr_bitmap_legacy);