Re: [PATCH] KVM: VMX: drop I/O permission bitmaps
From: Quan Xu
Date: Mon Dec 11 2017 - 00:15:47 EST
On 2017/12/09 00:18, David Hildenbrand wrote:
On 08.12.2017 11:22, Quan Xu wrote:
From: Quan Xu <quan.xu0@xxxxxxxxx>
Since KVM removes the only I/O port 0x80 bypass on Intel hosts,
clear CPU_BASED_USE_IO_BITMAPS and set CPU_BASED_UNCOND_IO_EXITING
bit. Then these I/O permission bitmaps are not used at all, so
drop I/O permission bitmaps.
Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
Signed-off-by: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
Signed-off-by: Quan Xu <quan.xu0@xxxxxxxxx>
---
arch/x86/kvm/vmx.c | 17 +----------------
1 files changed, 1 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 2fd9a8c..3e4f760 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -771,8 +771,6 @@ enum segment_cache_field {
FIELD(HOST_FS_SELECTOR, host_fs_selector),
FIELD(HOST_GS_SELECTOR, host_gs_selector),
FIELD(HOST_TR_SELECTOR, host_tr_selector),
- FIELD64(IO_BITMAP_A, io_bitmap_a),
- FIELD64(IO_BITMAP_B, io_bitmap_b),
FIELD64(MSR_BITMAP, msr_bitmap),
FIELD64(VM_EXIT_MSR_STORE_ADDR, vm_exit_msr_store_addr),
FIELD64(VM_EXIT_MSR_LOAD_ADDR, vm_exit_msr_load_addr),
@@ -943,8 +941,6 @@ static bool nested_vmx_is_page_fault_vmexit(struct vmcs12 *vmcs12,
static DEFINE_PER_CPU(spinlock_t, blocked_vcpu_on_cpu_lock);
enum {
- VMX_IO_BITMAP_A,
- VMX_IO_BITMAP_B,
VMX_MSR_BITMAP_LEGACY,
VMX_MSR_BITMAP_LONGMODE,
VMX_MSR_BITMAP_LEGACY_X2APIC_APICV,
@@ -958,8 +954,6 @@ enum {
static unsigned long *vmx_bitmap[VMX_BITMAP_NR];
-#define vmx_io_bitmap_a (vmx_bitmap[VMX_IO_BITMAP_A])
-#define vmx_io_bitmap_b (vmx_bitmap[VMX_IO_BITMAP_B])
#define vmx_msr_bitmap_legacy (vmx_bitmap[VMX_MSR_BITMAP_LEGACY])
#define vmx_msr_bitmap_longmode (vmx_bitmap[VMX_MSR_BITMAP_LONGMODE])
#define vmx_msr_bitmap_legacy_x2apic_apicv (vmx_bitmap[VMX_MSR_BITMAP_LEGACY_X2APIC_APICV])
@@ -3632,7 +3626,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
#endif
CPU_BASED_CR3_LOAD_EXITING |
CPU_BASED_CR3_STORE_EXITING |
- CPU_BASED_USE_IO_BITMAPS |
+ CPU_BASED_UNCOND_IO_EXITING |
CPU_BASED_MOV_DR_EXITING |
CPU_BASED_USE_TSC_OFFSETING |
CPU_BASED_INVLPG_EXITING |
@@ -5445,10 +5439,6 @@ static void vmx_vcpu_setup(struct vcpu_vmx *vmx)
#endif
int i;
- /* I/O */
- vmcs_write64(IO_BITMAP_A, __pa(vmx_io_bitmap_a));
- vmcs_write64(IO_BITMAP_B, __pa(vmx_io_bitmap_b));
-
if (enable_shadow_vmcs) {
vmcs_write64(VMREAD_BITMAP, __pa(vmx_vmread_bitmap));
vmcs_write64(VMWRITE_BITMAP, __pa(vmx_vmwrite_bitmap));
@@ -6751,14 +6741,9 @@ static __init int hardware_setup(void)
goto out;
}
- vmx_io_bitmap_b = (unsigned long *)__get_free_page(GFP_KERNEL);
memset(vmx_vmread_bitmap, 0xff, PAGE_SIZE);
memset(vmx_vmwrite_bitmap, 0xff, PAGE_SIZE);
- memset(vmx_io_bitmap_a, 0xff, PAGE_SIZE);
-
- memset(vmx_io_bitmap_b, 0xff, PAGE_SIZE);
-
memset(vmx_msr_bitmap_legacy, 0xff, PAGE_SIZE);
memset(vmx_msr_bitmap_longmode, 0xff, PAGE_SIZE);
Looks good to me.
David, thanks for your review.
We could now also drop
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index a5d2856eb28b..732e93332f4c 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10639,7 +10639,6 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu,
struct vmcs12 *vmcs12,
* Rather, exit every time.
*/
exec_control &= ~CPU_BASED_USE_IO_BITMAPS;
- exec_control |= CPU_BASED_UNCOND_IO_EXITING;
vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, exec_control);
As this will be implicitly set by vmx_exec_control()
good catch.
yes, L0 merge vmcs01 with vmcsl2 to create vmcs02 and run L2.
however as this code is related to nested virtualization, I better
introduce it in another new patch
with "KVM: NVMX" prefix subject after this patch is applied.
furthermore, I think I could drop these tow lines in another new patch:
- exec_control &= ~CPU_BASED_USE_IO_BITMAPS;
- exec_control |= CPU_BASED_UNCOND_IO_EXITING;
as the CPU_BASED_USE_IO_BITMAPS is clear after this patch.
Quan