[PATCH 026/104] KVM: VMX: Improve the method of writing vmcs control

From: Avi Kivity
Date: Mon Sep 17 2007 - 05:05:58 EST

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From: Yang, Sheng <sheng.yang@xxxxxxxxx>

Put cpu feature detecting part in hardware_setup, and stored the vmcs
condition in global variable for further check.

[glommer: fix for some i386-only machines not supporting CR8 load/store
exiting]

Signed-off-by: Sheng Yang <sheng.yang@xxxxxxxxx>
Signed-off-by: Glauber de Oliveira Costa <gcosta@xxxxxxxxxx>
Signed-off-by: Avi Kivity <avi@xxxxxxxxxxxx>
---
drivers/kvm/vmx.c | 147 ++++++++++++++++++++++++++++++++++++----------------
1 files changed, 102 insertions(+), 45 deletions(-)

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index df57878..18f9b0b 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -71,18 +71,17 @@ static DEFINE_PER_CPU(struct vmcs *, current_vmcs);
static struct page *vmx_io_bitmap_a;
static struct page *vmx_io_bitmap_b;

-#ifdef CONFIG_X86_64
-#define HOST_IS_64 1
-#else
-#define HOST_IS_64 0
-#endif
#define EFER_SAVE_RESTORE_BITS ((u64)EFER_SCE)

-static struct vmcs_descriptor {
+static struct vmcs_config {
int size;
int order;
u32 revision_id;
-} vmcs_descriptor;
+ u32 pin_based_exec_ctrl;
+ u32 cpu_based_exec_ctrl;
+ u32 vmexit_ctrl;
+ u32 vmentry_ctrl;
+} vmcs_config;

#define VMX_SEGMENT_FIELD(seg) \
[VCPU_SREG_##seg] = { \
@@ -839,14 +838,93 @@ static void hardware_disable(void *garbage)
asm volatile (ASM_VMX_VMXOFF : : : "cc");
}

-static __init void setup_vmcs_descriptor(void)
+static __init int adjust_vmx_controls(u32 ctl_min, u32 ctl_opt,
+ u32 msr, u32* result)
+{
+ u32 vmx_msr_low, vmx_msr_high;
+ u32 ctl = ctl_min | ctl_opt;
+
+ rdmsr(msr, vmx_msr_low, vmx_msr_high);
+
+ ctl &= vmx_msr_high; /* bit == 0 in high word ==> must be zero */
+ ctl |= vmx_msr_low; /* bit == 1 in low word ==> must be one */
+
+ /* Ensure minimum (required) set of control bits are supported. */
+ if (ctl_min & ~ctl)
+ return -1;
+
+ *result = ctl;
+ return 0;
+}
+
+static __init int setup_vmcs_config(void)
{
u32 vmx_msr_low, vmx_msr_high;
+ u32 min, opt;
+ u32 _pin_based_exec_control = 0;
+ u32 _cpu_based_exec_control = 0;
+ u32 _vmexit_control = 0;
+ u32 _vmentry_control = 0;
+
+ min = PIN_BASED_EXT_INTR_MASK | PIN_BASED_NMI_EXITING;
+ opt = 0;
+ if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_PINBASED_CTLS,
+ &_pin_based_exec_control) < 0)
+ return -1;
+
+ min = CPU_BASED_HLT_EXITING |
+#ifdef CONFIG_X86_64
+ CPU_BASED_CR8_LOAD_EXITING |
+ CPU_BASED_CR8_STORE_EXITING |
+#endif
+ CPU_BASED_USE_IO_BITMAPS |
+ CPU_BASED_MOV_DR_EXITING |
+ CPU_BASED_USE_TSC_OFFSETING;
+ opt = 0;
+ if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_PROCBASED_CTLS,
+ &_cpu_based_exec_control) < 0)
+ return -1;
+
+ min = 0;
+#ifdef CONFIG_X86_64
+ min |= VM_EXIT_HOST_ADDR_SPACE_SIZE;
+#endif
+ opt = 0;
+ if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_EXIT_CTLS,
+ &_vmexit_control) < 0)
+ return -1;
+
+ min = opt = 0;
+ if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_ENTRY_CTLS,
+ &_vmentry_control) < 0)
+ return -1;

rdmsr(MSR_IA32_VMX_BASIC, vmx_msr_low, vmx_msr_high);
- vmcs_descriptor.size = vmx_msr_high & 0x1fff;
- vmcs_descriptor.order = get_order(vmcs_descriptor.size);
- vmcs_descriptor.revision_id = vmx_msr_low;
+
+ /* IA-32 SDM Vol 3B: VMCS size is never greater than 4kB. */
+ if ((vmx_msr_high & 0x1fff) > PAGE_SIZE)
+ return -1;
+
+#ifdef CONFIG_X86_64
+ /* IA-32 SDM Vol 3B: 64-bit CPUs always have VMX_BASIC_MSR[48]==0. */
+ if (vmx_msr_high & (1u<<16))
+ return -1;
+#endif
+
+ /* Require Write-Back (WB) memory type for VMCS accesses. */
+ if (((vmx_msr_high >> 18) & 15) != 6)
+ return -1;
+
+ vmcs_config.size = vmx_msr_high & 0x1fff;
+ vmcs_config.order = get_order(vmcs_config.size);
+ vmcs_config.revision_id = vmx_msr_low;
+
+ vmcs_config.pin_based_exec_ctrl = _pin_based_exec_control;
+ vmcs_config.cpu_based_exec_ctrl = _cpu_based_exec_control;
+ vmcs_config.vmexit_ctrl = _vmexit_control;
+ vmcs_config.vmentry_ctrl = _vmentry_control;
+
+ return 0;
}

static struct vmcs *alloc_vmcs_cpu(int cpu)
@@ -855,12 +933,12 @@ static struct vmcs *alloc_vmcs_cpu(int cpu)
struct page *pages;
struct vmcs *vmcs;

- pages = alloc_pages_node(node, GFP_KERNEL, vmcs_descriptor.order);
+ pages = alloc_pages_node(node, GFP_KERNEL, vmcs_config.order);
if (!pages)
return NULL;
vmcs = page_address(pages);
- memset(vmcs, 0, vmcs_descriptor.size);
- vmcs->revision_id = vmcs_descriptor.revision_id; /* vmcs revision id */
+ memset(vmcs, 0, vmcs_config.size);
+ vmcs->revision_id = vmcs_config.revision_id; /* vmcs revision id */
return vmcs;
}

@@ -871,7 +949,7 @@ static struct vmcs *alloc_vmcs(void)

static void free_vmcs(struct vmcs *vmcs)
{
- free_pages((unsigned long)vmcs, vmcs_descriptor.order);
+ free_pages((unsigned long)vmcs, vmcs_config.order);
}

static void free_kvm_area(void)
@@ -904,7 +982,8 @@ static __init int alloc_kvm_area(void)

static __init int hardware_setup(void)
{
- setup_vmcs_descriptor();
+ if (setup_vmcs_config() < 0)
+ return -1;
return alloc_kvm_area();
}

@@ -1275,17 +1354,6 @@ static int init_rmode_tss(struct kvm* kvm)
return 1;
}

-static void vmcs_write32_fixedbits(u32 msr, u32 vmcs_field, u32 val)
-{
- u32 msr_high, msr_low;
-
- rdmsr(msr, msr_low, msr_high);
-
- val &= msr_high;
- val |= msr_low;
- vmcs_write32(vmcs_field, val);
-}
-
static void seg_setup(int seg)
{
struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];
@@ -1382,20 +1450,10 @@ static int vmx_vcpu_setup(struct kvm_vcpu *vcpu)
vmcs_write64(GUEST_IA32_DEBUGCTL, 0);

/* Control */
- vmcs_write32_fixedbits(MSR_IA32_VMX_PINBASED_CTLS,
- PIN_BASED_VM_EXEC_CONTROL,
- PIN_BASED_EXT_INTR_MASK /* 20.6.1 */
- | PIN_BASED_NMI_EXITING /* 20.6.1 */
- );
- vmcs_write32_fixedbits(MSR_IA32_VMX_PROCBASED_CTLS,
- CPU_BASED_VM_EXEC_CONTROL,
- CPU_BASED_HLT_EXITING /* 20.6.2 */
- | CPU_BASED_CR8_LOAD_EXITING /* 20.6.2 */
- | CPU_BASED_CR8_STORE_EXITING /* 20.6.2 */
- | CPU_BASED_USE_IO_BITMAPS /* 20.6.2 */
- | CPU_BASED_MOV_DR_EXITING
- | CPU_BASED_USE_TSC_OFFSETING /* 21.3 */
- );
+ vmcs_write32(PIN_BASED_VM_EXEC_CONTROL,
+ vmcs_config.pin_based_exec_ctrl);
+ vmcs_write32(CPU_BASED_VM_EXEC_CONTROL,
+ vmcs_config.cpu_based_exec_ctrl);

vmcs_write32(PAGE_FAULT_ERROR_CODE_MASK, 0);
vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH, 0);
@@ -1459,12 +1517,11 @@ static int vmx_vcpu_setup(struct kvm_vcpu *vcpu)

setup_msrs(vcpu);

- vmcs_write32_fixedbits(MSR_IA32_VMX_EXIT_CTLS, VM_EXIT_CONTROLS,
- (HOST_IS_64 << 9)); /* 22.2,1, 20.7.1 */
+ vmcs_write32(VM_EXIT_CONTROLS, vmcs_config.vmexit_ctrl);

/* 22.2.1, 20.8.1 */
- vmcs_write32_fixedbits(MSR_IA32_VMX_ENTRY_CTLS,
- VM_ENTRY_CONTROLS, 0);
+ vmcs_write32(VM_ENTRY_CONTROLS, vmcs_config.vmentry_ctrl);
+
vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, 0); /* 22.2.1 */

#ifdef CONFIG_X86_64
--
1.5.3

-
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Next message: Avi Kivity: "[PATCH 021/104] KVM: VMX: Import some constants of vmcs from IA32 SDM"
Previous message: Avi Kivity: "[PATCH 029/104] KVM: Convert vm lock to a mutex"
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