[RFC PATCH v3 50/59] KVM: VMX: Move AR_BYTES encoder/decoder helpers to common.h

isaku.yamahata
2021-11-25T00:22:54Z

From: Sean Christopherson <sean.j.christopherson@intel.com>

Move the AR_BYTES helpers to common.h so that future patches can reuse
them to decode/encode AR for TDX.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
arch/x86/kvm/vmx/common.h | 41 ++++++++++++++++++++++++++++++++++
arch/x86/kvm/vmx/vmx.c | 47 ++++-----------------------------------
2 files changed, 45 insertions(+), 43 deletions(-)

diff --git a/arch/x86/kvm/vmx/common.h b/arch/x86/kvm/vmx/common.h
index d37ef4dd9d90..e45d2d222168 100644
--- a/arch/x86/kvm/vmx/common.h
+++ b/arch/x86/kvm/vmx/common.h
@@ -4,6 +4,7 @@

#include <linux/kvm_host.h>

+#include <asm/kvm.h>
#include <asm/traps.h>
#include <asm/vmx.h>

@@ -119,4 +120,44 @@ static inline int __vmx_handle_ept_violation(struct kvm_vcpu *vcpu, gpa_t gpa,
return kvm_mmu_page_fault(vcpu, gpa, error_code, NULL, 0);
}

+static inline u32 vmx_encode_ar_bytes(struct kvm_segment *var)
+{
+ u32 ar;
+
+ if (var->unusable || !var->present)
+ ar = 1 << 16;
+ else {
+ ar = var->type & 15;
+ ar |= (var->s & 1) << 4;
+ ar |= (var->dpl & 3) << 5;
+ ar |= (var->present & 1) << 7;
+ ar |= (var->avl & 1) << 12;
+ ar |= (var->l & 1) << 13;
+ ar |= (var->db & 1) << 14;
+ ar |= (var->g & 1) << 15;
+ }
+
+ return ar;
+}
+
+static inline void vmx_decode_ar_bytes(u32 ar, struct kvm_segment *var)
+{
+ var->unusable = (ar >> 16) & 1;
+ var->type = ar & 15;
+ var->s = (ar >> 4) & 1;
+ var->dpl = (ar >> 5) & 3;
+ /*
+ * Some userspaces do not preserve unusable property. Since usable
+ * segment has to be present according to VMX spec we can use present
+ * property to amend userspace bug by making unusable segment always
+ * nonpresent. vmx_encode_ar_bytes() already marks nonpresent
+ * segment as unusable.
+ */
+ var->present = !var->unusable;
+ var->avl = (ar >> 12) & 1;
+ var->l = (ar >> 13) & 1;
+ var->db = (ar >> 14) & 1;
+ var->g = (ar >> 15) & 1;
+}
+
#endif /* __KVM_X86_VMX_COMMON_H */
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 98710b578b28..6f98d1b2a498 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -365,8 +365,6 @@ static const struct kernel_param_ops vmentry_l1d_flush_ops = {
};
module_param_cb(vmentry_l1d_flush, &vmentry_l1d_flush_ops, NULL, 0644);

-static u32 vmx_segment_access_rights(struct kvm_segment *var);
-
void vmx_vmexit(void);

#define vmx_insn_failed(fmt...) \
@@ -2730,7 +2728,7 @@ static void fix_rmode_seg(int seg, struct kvm_segment *save)
vmcs_write16(sf->selector, var.selector);
vmcs_writel(sf->base, var.base);
vmcs_write32(sf->limit, var.limit);
- vmcs_write32(sf->ar_bytes, vmx_segment_access_rights(&var));
+ vmcs_write32(sf->ar_bytes, vmx_encode_ar_bytes(&var));
}

static void enter_rmode(struct kvm_vcpu *vcpu)
@@ -3138,7 +3136,6 @@ void vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
void vmx_get_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
- u32 ar;

if (vmx->rmode.vm86_active && seg != VCPU_SREG_LDTR) {
*var = vmx->rmode.segs[seg];
@@ -3152,23 +3149,7 @@ void vmx_get_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg)
var->base = vmx_read_guest_seg_base(vmx, seg);
var->limit = vmx_read_guest_seg_limit(vmx, seg);
var->selector = vmx_read_guest_seg_selector(vmx, seg);
- ar = vmx_read_guest_seg_ar(vmx, seg);
- var->unusable = (ar >> 16) & 1;
- var->type = ar & 15;
- var->s = (ar >> 4) & 1;
- var->dpl = (ar >> 5) & 3;
- /*
- * Some userspaces do not preserve unusable property. Since usable
- * segment has to be present according to VMX spec we can use present
- * property to amend userspace bug by making unusable segment always
- * nonpresent. vmx_segment_access_rights() already marks nonpresent
- * segment as unusable.
- */
- var->present = !var->unusable;
- var->avl = (ar >> 12) & 1;
- var->l = (ar >> 13) & 1;
- var->db = (ar >> 14) & 1;
- var->g = (ar >> 15) & 1;
+ vmx_decode_ar_bytes(vmx_read_guest_seg_ar(vmx, seg), var);
}

u64 vmx_get_segment_base(struct kvm_vcpu *vcpu, int seg)
@@ -3194,26 +3175,6 @@ int vmx_get_cpl(struct kvm_vcpu *vcpu)
}
}

-static u32 vmx_segment_access_rights(struct kvm_segment *var)
-{
- u32 ar;
-
- if (var->unusable || !var->present)
- ar = 1 << 16;
- else {
- ar = var->type & 15;
- ar |= (var->s & 1) << 4;
- ar |= (var->dpl & 3) << 5;
- ar |= (var->present & 1) << 7;
- ar |= (var->avl & 1) << 12;
- ar |= (var->l & 1) << 13;
- ar |= (var->db & 1) << 14;
- ar |= (var->g & 1) << 15;
- }
-
- return ar;
-}
-
void __vmx_set_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -3248,7 +3209,7 @@ void __vmx_set_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg)
if (is_unrestricted_guest(vcpu) && (seg != VCPU_SREG_LDTR))
var->type |= 0x1; /* Accessed */

- vmcs_write32(sf->ar_bytes, vmx_segment_access_rights(var));
+ vmcs_write32(sf->ar_bytes, vmx_encode_ar_bytes(var));
}

void vmx_set_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg)
@@ -3299,7 +3260,7 @@ static bool rmode_segment_valid(struct kvm_vcpu *vcpu, int seg)
var.dpl = 0x3;
if (seg == VCPU_SREG_CS)
var.type = 0x3;
- ar = vmx_segment_access_rights(&var);
+ ar = vmx_encode_ar_bytes(&var);

if (var.base != (var.selector << 4))
return false;
--
2.25.1