[PATCH v2] KVM: x86: Modify struct kvm_nested_state to have explicit fields for data
From: Paolo Bonzini
Date: Tue Jun 18 2019 - 12:29:17 EST
From: Liran Alon <liran.alon@xxxxxxxxxx>
Improve the KVM_{GET,SET}_NESTED_STATE structs by detailing the format
of VMX nested state data in a struct.
In order to avoid changing the ioctl values of
KVM_{GET,SET}_NESTED_STATE, there is a need to preserve
sizeof(struct kvm_nested_state). This is done by defining the data
struct as "data.vmx[0]". It was the most elegant way I found to
preserve struct size while still keeping struct readable and easy to
maintain. It does have a misfortunate side-effect that now it has to be
accessed as "data.vmx[0]" rather than just "data.vmx".
Because we are already modifying these structs, I also modified the
following:
* Define the "format" field values as macros.
* Rename vmcs_pa to vmcs12_pa for better readability.
Signed-off-by: Liran Alon <liran.alon@xxxxxxxxxx>
[Remove SVM stubs, add KVM_STATE_NESTED_VMX_VMCS12_SIZE. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
Documentation/virtual/kvm/api.txt | 46 +++++++++++++-------
arch/x86/include/uapi/asm/kvm.h | 33 ++++++++++-----
arch/x86/kvm/vmx/nested.c | 79 +++++++++++++++++++----------------
arch/x86/kvm/vmx/vmcs12.h | 5 ++-
tools/arch/x86/include/uapi/asm/kvm.h | 2 +-
5 files changed, 101 insertions(+), 64 deletions(-)
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index f5616b441af8..2a4531bb06bd 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3857,43 +3857,59 @@ Type: vcpu ioctl
Parameters: struct kvm_nested_state (in/out)
Returns: 0 on success, -1 on error
Errors:
- E2BIG: the total state size (including the fixed-size part of struct
- kvm_nested_state) exceeds the value of 'size' specified by
+ E2BIG: the total state size exceeds the value of 'size' specified by
the user; the size required will be written into size.
struct kvm_nested_state {
__u16 flags;
__u16 format;
__u32 size;
+
union {
- struct kvm_vmx_nested_state vmx;
- struct kvm_svm_nested_state svm;
+ struct kvm_vmx_nested_state_hdr vmx;
+ struct kvm_svm_nested_state_hdr svm;
+
+ /* Pad the header to 128 bytes. */
__u8 pad[120];
- };
- __u8 data[0];
+ } hdr;
+
+ union {
+ struct kvm_vmx_nested_state_data vmx[0];
+ struct kvm_svm_nested_state_data svm[0];
+ } data;
};
#define KVM_STATE_NESTED_GUEST_MODE 0x00000001
#define KVM_STATE_NESTED_RUN_PENDING 0x00000002
+#define KVM_STATE_NESTED_EVMCS 0x00000004
-#define KVM_STATE_NESTED_SMM_GUEST_MODE 0x00000001
-#define KVM_STATE_NESTED_SMM_VMXON 0x00000002
+#define KVM_STATE_NESTED_FORMAT_VMX 0
+#define KVM_STATE_NESTED_FORMAT_SVM 1
-struct kvm_vmx_nested_state {
+#define KVM_STATE_NESTED_VMX_VMCS_SIZE 0x1000
+
+#define KVM_STATE_NESTED_VMX_SMM_GUEST_MODE 0x00000001
+#define KVM_STATE_NESTED_VMX_SMM_VMXON 0x00000002
+
+struct kvm_vmx_nested_state_hdr {
__u64 vmxon_pa;
- __u64 vmcs_pa;
+ __u64 vmcs12_pa;
struct {
__u16 flags;
} smm;
};
+struct kvm_vmx_nested_state_data {
+ __u8 vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
+ __u8 shadow_vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
+};
+
This ioctl copies the vcpu's nested virtualization state from the kernel to
userspace.
-The maximum size of the state, including the fixed-size part of struct
-kvm_nested_state, can be retrieved by passing KVM_CAP_NESTED_STATE to
-the KVM_CHECK_EXTENSION ioctl().
+The maximum size of the state can be retrieved by passing KVM_CAP_NESTED_STATE
+to the KVM_CHECK_EXTENSION ioctl().
4.115 KVM_SET_NESTED_STATE
@@ -3903,8 +3919,8 @@ Type: vcpu ioctl
Parameters: struct kvm_nested_state (in)
Returns: 0 on success, -1 on error
-This copies the vcpu's kvm_nested_state struct from userspace to the kernel. For
-the definition of struct kvm_nested_state, see KVM_GET_NESTED_STATE.
+This copies the vcpu's kvm_nested_state struct from userspace to the kernel.
+For the definition of struct kvm_nested_state, see KVM_GET_NESTED_STATE.
4.116 KVM_(UN)REGISTER_COALESCED_MMIO
diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 7a0e64ccd6ff..d6ab5b4d15e5 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -383,6 +383,9 @@ struct kvm_sync_regs {
#define KVM_X86_QUIRK_LAPIC_MMIO_HOLE (1 << 2)
#define KVM_X86_QUIRK_OUT_7E_INC_RIP (1 << 3)
+#define KVM_STATE_NESTED_FORMAT_VMX 0
+#define KVM_STATE_NESTED_FORMAT_SVM 1 /* unused */
+
#define KVM_STATE_NESTED_GUEST_MODE 0x00000001
#define KVM_STATE_NESTED_RUN_PENDING 0x00000002
#define KVM_STATE_NESTED_EVMCS 0x00000004
@@ -390,9 +393,16 @@ struct kvm_sync_regs {
#define KVM_STATE_NESTED_SMM_GUEST_MODE 0x00000001
#define KVM_STATE_NESTED_SMM_VMXON 0x00000002
-struct kvm_vmx_nested_state {
+#define KVM_STATE_NESTED_VMX_VMCS_SIZE 0x1000
+
+struct kvm_vmx_nested_state_data {
+ __u8 vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
+ __u8 shadow_vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
+};
+
+struct kvm_vmx_nested_state_hdr {
__u64 vmxon_pa;
- __u64 vmcs_pa;
+ __u64 vmcs12_pa;
struct {
__u16 flags;
@@ -401,24 +411,25 @@ struct kvm_vmx_nested_state {
/* for KVM_CAP_NESTED_STATE */
struct kvm_nested_state {
- /* KVM_STATE_* flags */
__u16 flags;
-
- /* 0 for VMX, 1 for SVM. */
__u16 format;
-
- /* 128 for SVM, 128 + VMCS size for VMX. */
__u32 size;
union {
- /* VMXON, VMCS */
- struct kvm_vmx_nested_state vmx;
+ struct kvm_vmx_nested_state_hdr vmx;
/* Pad the header to 128 bytes. */
__u8 pad[120];
- };
+ } hdr;
- __u8 data[0];
+ /*
+ * Define data region as 0 bytes to preserve backwards-compatability
+ * to old definition of kvm_nested_state in order to avoid changing
+ * KVM_{GET,PUT}_NESTED_STATE ioctl values.
+ */
+ union {
+ struct kvm_vmx_nested_state_data vmx[0];
+ } data;
};
#endif /* _ASM_X86_KVM_H */
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index d3940da3d435..fb6d1f7b43f3 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -5226,14 +5226,16 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
struct vmcs12 *vmcs12;
struct kvm_nested_state kvm_state = {
.flags = 0,
- .format = 0,
+ .format = KVM_STATE_NESTED_FORMAT_VMX,
.size = sizeof(kvm_state),
- .vmx.vmxon_pa = -1ull,
- .vmx.vmcs_pa = -1ull,
+ .hdr.vmx.vmxon_pa = -1ull,
+ .hdr.vmx.vmcs12_pa = -1ull,
};
+ struct kvm_vmx_nested_state_data __user *user_vmx_nested_state =
+ &user_kvm_nested_state->data.vmx[0];
if (!vcpu)
- return kvm_state.size + 2 * VMCS12_SIZE;
+ return kvm_state.size + sizeof(*user_vmx_nested_state);
vmx = to_vmx(vcpu);
vmcs12 = get_vmcs12(vcpu);
@@ -5243,23 +5245,23 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
if (nested_vmx_allowed(vcpu) &&
(vmx->nested.vmxon || vmx->nested.smm.vmxon)) {
- kvm_state.vmx.vmxon_pa = vmx->nested.vmxon_ptr;
- kvm_state.vmx.vmcs_pa = vmx->nested.current_vmptr;
+ kvm_state.hdr.vmx.vmxon_pa = vmx->nested.vmxon_ptr;
+ kvm_state.hdr.vmx.vmcs12_pa = vmx->nested.current_vmptr;
if (vmx_has_valid_vmcs12(vcpu)) {
- kvm_state.size += VMCS12_SIZE;
+ kvm_state.size += sizeof(user_vmx_nested_state->vmcs12);
if (is_guest_mode(vcpu) &&
nested_cpu_has_shadow_vmcs(vmcs12) &&
vmcs12->vmcs_link_pointer != -1ull)
- kvm_state.size += VMCS12_SIZE;
+ kvm_state.size += sizeof(user_vmx_nested_state->shadow_vmcs12);
}
if (vmx->nested.smm.vmxon)
- kvm_state.vmx.smm.flags |= KVM_STATE_NESTED_SMM_VMXON;
+ kvm_state.hdr.vmx.smm.flags |= KVM_STATE_NESTED_SMM_VMXON;
if (vmx->nested.smm.guest_mode)
- kvm_state.vmx.smm.flags |= KVM_STATE_NESTED_SMM_GUEST_MODE;
+ kvm_state.hdr.vmx.smm.flags |= KVM_STATE_NESTED_SMM_GUEST_MODE;
if (is_guest_mode(vcpu)) {
kvm_state.flags |= KVM_STATE_NESTED_GUEST_MODE;
@@ -5294,16 +5296,19 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
copy_shadow_to_vmcs12(vmx);
}
+ BUILD_BUG_ON(sizeof(user_vmx_nested_state->vmcs12) < VMCS12_SIZE);
+ BUILD_BUG_ON(sizeof(user_vmx_nested_state->shadow_vmcs12) < VMCS12_SIZE);
+
/*
* Copy over the full allocated size of vmcs12 rather than just the size
* of the struct.
*/
- if (copy_to_user(user_kvm_nested_state->data, vmcs12, VMCS12_SIZE))
+ if (copy_to_user(user_vmx_nested_state->vmcs12, vmcs12, VMCS12_SIZE))
return -EFAULT;
if (nested_cpu_has_shadow_vmcs(vmcs12) &&
vmcs12->vmcs_link_pointer != -1ull) {
- if (copy_to_user(user_kvm_nested_state->data + VMCS12_SIZE,
+ if (copy_to_user(user_vmx_nested_state->shadow_vmcs12,
get_shadow_vmcs12(vcpu), VMCS12_SIZE))
return -EFAULT;
}
@@ -5331,33 +5336,35 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
struct vcpu_vmx *vmx = to_vmx(vcpu);
struct vmcs12 *vmcs12;
u32 exit_qual;
+ struct kvm_vmx_nested_state_data __user *user_vmx_nested_state =
+ &user_kvm_nested_state->data.vmx[0];
int ret;
- if (kvm_state->format != 0)
+ if (kvm_state->format != KVM_STATE_NESTED_FORMAT_VMX)
return -EINVAL;
if (!nested_vmx_allowed(vcpu))
- return kvm_state->vmx.vmxon_pa == -1ull ? 0 : -EINVAL;
+ return kvm_state->hdr.vmx.vmxon_pa == -1ull ? 0 : -EINVAL;
- if (kvm_state->vmx.vmxon_pa == -1ull) {
- if (kvm_state->vmx.smm.flags)
+ if (kvm_state->hdr.vmx.vmxon_pa == -1ull) {
+ if (kvm_state->hdr.vmx.smm.flags)
return -EINVAL;
- if (kvm_state->vmx.vmcs_pa != -1ull)
+ if (kvm_state->hdr.vmx.vmcs12_pa != -1ull)
return -EINVAL;
vmx_leave_nested(vcpu);
return 0;
}
- if (!page_address_valid(vcpu, kvm_state->vmx.vmxon_pa))
+ if (!page_address_valid(vcpu, kvm_state->hdr.vmx.vmxon_pa))
return -EINVAL;
- if ((kvm_state->vmx.smm.flags & KVM_STATE_NESTED_SMM_GUEST_MODE) &&
+ if ((kvm_state->hdr.vmx.smm.flags & KVM_STATE_NESTED_SMM_GUEST_MODE) &&
(kvm_state->flags & KVM_STATE_NESTED_GUEST_MODE))
return -EINVAL;
- if (kvm_state->vmx.smm.flags &
+ if (kvm_state->hdr.vmx.smm.flags &
~(KVM_STATE_NESTED_SMM_GUEST_MODE | KVM_STATE_NESTED_SMM_VMXON))
return -EINVAL;
@@ -5366,21 +5373,21 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
* nor can VMLAUNCH/VMRESUME be pending. Outside SMM, SMM flags
* must be zero.
*/
- if (is_smm(vcpu) ? kvm_state->flags : kvm_state->vmx.smm.flags)
+ if (is_smm(vcpu) ? kvm_state->flags : kvm_state->hdr.vmx.smm.flags)
return -EINVAL;
- if ((kvm_state->vmx.smm.flags & KVM_STATE_NESTED_SMM_GUEST_MODE) &&
- !(kvm_state->vmx.smm.flags & KVM_STATE_NESTED_SMM_VMXON))
+ if ((kvm_state->hdr.vmx.smm.flags & KVM_STATE_NESTED_SMM_GUEST_MODE) &&
+ !(kvm_state->hdr.vmx.smm.flags & KVM_STATE_NESTED_SMM_VMXON))
return -EINVAL;
vmx_leave_nested(vcpu);
- if (kvm_state->vmx.vmxon_pa == -1ull)
+ if (kvm_state->hdr.vmx.vmxon_pa == -1ull)
return 0;
if (kvm_state->flags & KVM_STATE_NESTED_EVMCS)
nested_enable_evmcs(vcpu, NULL);
- vmx->nested.vmxon_ptr = kvm_state->vmx.vmxon_pa;
+ vmx->nested.vmxon_ptr = kvm_state->hdr.vmx.vmxon_pa;
ret = enter_vmx_operation(vcpu);
if (ret)
return ret;
@@ -5389,12 +5396,12 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
if (kvm_state->size < sizeof(*kvm_state) + sizeof(*vmcs12))
return 0;
- if (kvm_state->vmx.vmcs_pa != -1ull) {
- if (kvm_state->vmx.vmcs_pa == kvm_state->vmx.vmxon_pa ||
- !page_address_valid(vcpu, kvm_state->vmx.vmcs_pa))
+ if (kvm_state->hdr.vmx.vmcs12_pa != -1ull) {
+ if (kvm_state->hdr.vmx.vmcs12_pa == kvm_state->hdr.vmx.vmxon_pa ||
+ !page_address_valid(vcpu, kvm_state->hdr.vmx.vmcs12_pa))
return -EINVAL;
- set_current_vmptr(vmx, kvm_state->vmx.vmcs_pa);
+ set_current_vmptr(vmx, kvm_state->hdr.vmx.vmcs12_pa);
} else if (kvm_state->flags & KVM_STATE_NESTED_EVMCS) {
/*
* Sync eVMCS upon entry as we may not have
@@ -5405,16 +5412,16 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
return -EINVAL;
}
- if (kvm_state->vmx.smm.flags & KVM_STATE_NESTED_SMM_VMXON) {
+ if (kvm_state->hdr.vmx.smm.flags & KVM_STATE_NESTED_SMM_VMXON) {
vmx->nested.smm.vmxon = true;
vmx->nested.vmxon = false;
- if (kvm_state->vmx.smm.flags & KVM_STATE_NESTED_SMM_GUEST_MODE)
+ if (kvm_state->hdr.vmx.smm.flags & KVM_STATE_NESTED_SMM_GUEST_MODE)
vmx->nested.smm.guest_mode = true;
}
vmcs12 = get_vmcs12(vcpu);
- if (copy_from_user(vmcs12, user_kvm_nested_state->data, sizeof(*vmcs12)))
+ if (copy_from_user(vmcs12, user_vmx_nested_state->vmcs12, sizeof(*vmcs12)))
return -EFAULT;
if (vmcs12->hdr.revision_id != VMCS12_REVISION)
@@ -5431,12 +5438,14 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
vmcs12->vmcs_link_pointer != -1ull) {
struct vmcs12 *shadow_vmcs12 = get_shadow_vmcs12(vcpu);
- if (kvm_state->size < sizeof(*kvm_state) + VMCS12_SIZE + sizeof(*vmcs12))
+ if (kvm_state->size <
+ sizeof(*kvm_state) +
+ sizeof(user_vmx_nested_state->vmcs12) + sizeof(*shadow_vmcs12))
goto error_guest_mode;
if (copy_from_user(shadow_vmcs12,
- user_kvm_nested_state->data + VMCS12_SIZE,
- sizeof(*vmcs12))) {
+ user_vmx_nested_state->shadow_vmcs12,
+ sizeof(*shadow_vmcs12))) {
ret = -EFAULT;
goto error_guest_mode;
}
diff --git a/arch/x86/kvm/vmx/vmcs12.h b/arch/x86/kvm/vmx/vmcs12.h
index 3a742428ad17..337718fc8a36 100644
--- a/arch/x86/kvm/vmx/vmcs12.h
+++ b/arch/x86/kvm/vmx/vmcs12.h
@@ -201,9 +201,10 @@ struct __packed vmcs12 {
/*
* VMCS12_SIZE is the number of bytes L1 should allocate for the VMXON region
* and any VMCS region. Although only sizeof(struct vmcs12) are used by the
- * current implementation, 4K are reserved to avoid future complications.
+ * current implementation, 4K are reserved to avoid future complications and
+ * to preserve userspace ABI.
*/
-#define VMCS12_SIZE 0x1000
+#define VMCS12_SIZE KVM_STATE_NESTED_VMX_VMCS_SIZE
/*
* VMCS12_MAX_FIELD_INDEX is the highest index value used in any
diff --git a/tools/arch/x86/include/uapi/asm/kvm.h b/tools/arch/x86/include/uapi/asm/kvm.h
index 7a0e64ccd6ff..24a8cd229df6 100644
--- a/tools/arch/x86/include/uapi/asm/kvm.h
+++ b/tools/arch/x86/include/uapi/asm/kvm.h
@@ -392,7 +392,7 @@ struct kvm_sync_regs {
struct kvm_vmx_nested_state {
__u64 vmxon_pa;
- __u64 vmcs_pa;
+ __u64 vmcs12_pa;
struct {
__u16 flags;
--
1.8.3.1