Provide emulation for VMREAD and VMWRITE vmx instructions.
The VMREAD/VMWRITE of non-shadowing vmcs fields from host VM cause
vmexit. Add vmexit handlers to manage these non-shadowing vmcs fields,
mainly two different parts:
- emulated fields: record in cached_vmcs12 and set dirty_vmcs12 to
indicate emulation needed before vmcs02 take effect.
- host state fields: record in cached_vmcs12 and restore as guest
state for vmcs01 when return back to host VM.
Signed-off-by: Jason Chen CJ <jason.cj.chen@xxxxxxxxx>
---
arch/x86/include/asm/pkvm_image_vars.h | 3 +-
arch/x86/kvm/vmx/pkvm/hyp/nested.c | 138 +++++++++++++++++++++++++
arch/x86/kvm/vmx/pkvm/hyp/nested.h | 2 +
arch/x86/kvm/vmx/pkvm/hyp/vmexit.c | 10 ++
4 files changed, 152 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/pkvm_image_vars.h b/arch/x86/include/asm/pkvm_image_vars.h
index 598c60302bac..967ee323a5c0 100644
--- a/arch/x86/include/asm/pkvm_image_vars.h
+++ b/arch/x86/include/asm/pkvm_image_vars.h
@@ -16,7 +16,8 @@ PKVM_ALIAS(sme_me_mask);
#endif
PKVM_ALIAS(__default_kernel_pte_mask);
-
+PKVM_ALIAS(vmcs12_field_offsets);
+PKVM_ALIAS(nr_vmcs12_fields);
#endif
#endif
diff --git a/arch/x86/kvm/vmx/pkvm/hyp/nested.c b/arch/x86/kvm/vmx/pkvm/hyp/nested.c
index dab002ff3c68..fd8755621cc8 100644
--- a/arch/x86/kvm/vmx/pkvm/hyp/nested.c
+++ b/arch/x86/kvm/vmx/pkvm/hyp/nested.c
@@ -229,6 +229,18 @@ static bool is_host_fields(unsigned long field)
return (((field) >> 10U) & 0x3U) == 3U;
}
+static bool is_emulated_fields(unsigned long field_encoding)
+{
+ int i;
+
+ for (i = 0; i < max_emulated_fields; i++) {
+ if ((unsigned long)emulated_fields[i].encoding == field_encoding)
+ return true;
+ }
+
+ return false;
+}
+
static void nested_vmx_result(enum VMXResult result, int error_number)
{
u64 rflags = vmcs_readl(GUEST_RFLAGS);
@@ -671,6 +683,132 @@ int handle_vmclear(struct kvm_vcpu *vcpu)
return 0;
}
+int handle_vmwrite(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+ struct pkvm_host_vcpu *pkvm_hvcpu = to_pkvm_hvcpu(vcpu);
+ struct shadow_vcpu_state *cur_shadow_vcpu = pkvm_hvcpu->current_shadow_vcpu;
+ struct vmcs12 *vmcs12 = (struct vmcs12 *)cur_shadow_vcpu->cached_vmcs12;
+ u32 instr_info = vmcs_read32(VMX_INSTRUCTION_INFO);
+ struct x86_exception e;
+ unsigned long field;
+ short offset;
+ gva_t gva;
+ int r, reg;
+ u64 value = 0;
+
+ if (check_vmx_permission(vcpu)) {
+ if (vmx->nested.current_vmptr == INVALID_GPA) {
+ nested_vmx_result(VMfailInvalid, 0);
+ } else {
+ if (instr_info & BIT(10)) {
+ reg = ((instr_info) >> 3) & 0xf;
+ value = vcpu->arch.regs[reg];
+ } else {
+ if (get_vmx_mem_address(vcpu, vmx->exit_qualification,
+ instr_info, &gva))
+ return 1;
+
+ r = read_gva(vcpu, gva, &value, 8, &e);
+ if (r < 0) {
+ /*TODO: handle memory failure exception */
+ return r;
+ }
+ }
+
+ reg = ((instr_info) >> 28) & 0xf;
+ field = vcpu->arch.regs[reg];
+
+ offset = get_vmcs12_field_offset(field);
+ if (offset < 0) {
+ nested_vmx_result(VMfailInvalid, VMXERR_UNSUPPORTED_VMCS_COMPONENT);
+ return 0;
+ }
+
+ /*TODO: check vcpu supports "VMWRITE to any supported field in the VMCS"*/
+ if (vmcs_field_readonly(field)) {
+ nested_vmx_result(VMfailInvalid, VMXERR_VMWRITE_READ_ONLY_VMCS_COMPONENT);
+ return 0;
+ }
+
+ /*
+ * Some Intel CPUs intentionally drop the reserved bits of the AR byte
+ * fields on VMWRITE. Emulate this behavior to ensure consistent KVM
+ * behavior regardless of the underlying hardware, e.g. if an AR_BYTE
+ * field is intercepted for VMWRITE but not VMREAD (in L1), then VMREAD
+ * from L1 will return a different value than VMREAD from L2 (L1 sees
+ * the stripped down value, L2 sees the full value as stored by KVM).
+ */
+ if (field >= GUEST_ES_AR_BYTES && field <= GUEST_TR_AR_BYTES)
+ value &= 0x1f0ff;
+
+ vmcs12_write_any(vmcs12, field, offset, value);
+
+ if (is_emulated_fields(field)) {
+ vmx->nested.dirty_vmcs12 = true;
+ nested_vmx_result(VMsucceed, 0);
+ } else if (is_host_fields(field)) {
+ nested_vmx_result(VMsucceed, 0);
+ } else {
+ pkvm_err("%s: not include emulated fields 0x%lx, please add!\n",
+ __func__, field);
+ nested_vmx_result(VMfailInvalid, VMXERR_UNSUPPORTED_VMCS_COMPONENT);
+ }
+ }
+ }
+
+ return 0;
+}
+
+int handle_vmread(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+ struct pkvm_host_vcpu *pkvm_hvcpu = to_pkvm_hvcpu(vcpu);
+ struct shadow_vcpu_state *cur_shadow_vcpu = pkvm_hvcpu->current_shadow_vcpu;
+ struct vmcs12 *vmcs12 = (struct vmcs12 *)cur_shadow_vcpu->cached_vmcs12;
+ u32 instr_info = vmcs_read32(VMX_INSTRUCTION_INFO);
+ struct x86_exception e;
+ unsigned long field;
+ short offset;
+ gva_t gva = 0;
+ int r, reg;
+ u64 value;
+
+ if (check_vmx_permission(vcpu)) {
+ if (vmx->nested.current_vmptr == INVALID_GPA) {
+ nested_vmx_result(VMfailInvalid, 0);
+ } else {
+ /* Decode instruction info and find the field to read */
+ reg = ((instr_info) >> 28) & 0xf;
+ field = vcpu->arch.regs[reg];
+
+ offset = get_vmcs12_field_offset(field);
+ if (offset < 0) {
+ nested_vmx_result(VMfailInvalid, VMXERR_UNSUPPORTED_VMCS_COMPONENT);
+ } else {
+ value = vmcs12_read_any(vmcs12, field, offset);
+ if (instr_info & BIT(10)) {
+ reg = ((instr_info) >> 3) & 0xf;
+ vcpu->arch.regs[reg] = value;
+ } else {
+ if (get_vmx_mem_address(vcpu, vmx->exit_qualification,
+ instr_info, &gva))
+ return 1;
+
+ r = write_gva(vcpu, gva, &value, 8, &e);
+ if (r < 0) {
+ /*TODO: handle memory failure exception */
+ return r;
+ }
+ }
+ nested_vmx_result(VMsucceed, 0);
+ }
+ }
+ }
+
+ return 0;
+}
+
void pkvm_init_nest(void)
{
init_vmcs_shadow_fields();
diff --git a/arch/x86/kvm/vmx/pkvm/hyp/nested.h b/arch/x86/kvm/vmx/pkvm/hyp/nested.h
index a228b0fdc15d..5fc76bdb135a 100644
--- a/arch/x86/kvm/vmx/pkvm/hyp/nested.h
+++ b/arch/x86/kvm/vmx/pkvm/hyp/nested.h
@@ -9,6 +9,8 @@ int handle_vmxon(struct kvm_vcpu *vcpu);
int handle_vmxoff(struct kvm_vcpu *vcpu);
int handle_vmptrld(struct kvm_vcpu *vcpu);
int handle_vmclear(struct kvm_vcpu *vcpu);
+int handle_vmwrite(struct kvm_vcpu *vcpu);
+int handle_vmread(struct kvm_vcpu *vcpu);
void pkvm_init_nest(void);
#endif
diff --git a/arch/x86/kvm/vmx/pkvm/hyp/vmexit.c b/arch/x86/kvm/vmx/pkvm/hyp/vmexit.c
index b2cfb87983a8..d4f2a408e6e9 100644
--- a/arch/x86/kvm/vmx/pkvm/hyp/vmexit.c
+++ b/arch/x86/kvm/vmx/pkvm/hyp/vmexit.c
@@ -216,6 +216,16 @@ int pkvm_main(struct kvm_vcpu *vcpu)
handle_vmclear(vcpu);
skip_instruction = true;
break;
+ case EXIT_REASON_VMREAD:
+ pkvm_dbg("CPU%d vmexit reason: WMREAD.\n", vcpu->cpu);
+ handle_vmread(vcpu);
+ skip_instruction = true;
+ break;
+ case EXIT_REASON_VMWRITE:
+ pkvm_dbg("CPU%d vmexit reason: VMWRITE.\n", vcpu->cpu);
+ handle_vmwrite(vcpu);
+ skip_instruction = true;
+ break;
case EXIT_REASON_XSETBV:
handle_xsetbv(vcpu);
skip_instruction = true;
--
2.25.1
