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KVM: SVM: Provide helpers to set the error code
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Provide helpers to set the error code when converting VMGEXIT SW_EXITINFO1 and
SW_EXITINFO2 codes from plain numbers to proper defines. Add comments for
better code readability.

No functionality changed.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Melody Wang <huibo.wang@amd.com>
Link: https://lore.kernel.org/r/20250225213937.2471419-3-huibo.wang@amd.com
[sean: tweak comments, fix formatting goofs]
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Melody Wang authored and Sean Christopherson committed Feb 26, 2025
1 parent ea4c2f2 commit c3392d0
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Showing 3 changed files with 49 additions and 23 deletions.
37 changes: 19 additions & 18 deletions arch/x86/kvm/svm/sev.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3410,8 +3410,7 @@ static int sev_es_validate_vmgexit(struct vcpu_svm *svm)
dump_ghcb(svm);
}

ghcb_set_sw_exit_info_1(svm->sev_es.ghcb, GHCB_HV_RESP_MALFORMED_INPUT);
ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, reason);
svm_vmgexit_bad_input(svm, reason);

/* Resume the guest to "return" the error code. */
return 1;
Expand Down Expand Up @@ -3554,8 +3553,7 @@ static int setup_vmgexit_scratch(struct vcpu_svm *svm, bool sync, u64 len)
return 0;

e_scratch:
ghcb_set_sw_exit_info_1(svm->sev_es.ghcb, GHCB_HV_RESP_MALFORMED_INPUT);
ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, GHCB_ERR_INVALID_SCRATCH_AREA);
svm_vmgexit_bad_input(svm, GHCB_ERR_INVALID_SCRATCH_AREA);

return 1;
}
Expand Down Expand Up @@ -3655,7 +3653,14 @@ static void snp_complete_psc(struct vcpu_svm *svm, u64 psc_ret)
svm->sev_es.psc_inflight = 0;
svm->sev_es.psc_idx = 0;
svm->sev_es.psc_2m = false;
ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, psc_ret);

/*
* PSC requests always get a "no action" response in SW_EXITINFO1, with
* a PSC-specific return code in SW_EXITINFO2 that provides the "real"
* return code. E.g. if the PSC request was interrupted, the need to
* retry is communicated via SW_EXITINFO2, not SW_EXITINFO1.
*/
svm_vmgexit_no_action(svm, psc_ret);
}

static void __snp_complete_one_psc(struct vcpu_svm *svm)
Expand Down Expand Up @@ -4058,7 +4063,8 @@ static int snp_handle_guest_req(struct vcpu_svm *svm, gpa_t req_gpa, gpa_t resp_
goto out_unlock;
}

ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, SNP_GUEST_ERR(0, fw_err));
/* No action is requested *from KVM* if there was a firmware error. */
svm_vmgexit_no_action(svm, SNP_GUEST_ERR(0, fw_err));

ret = 1; /* resume guest */

Expand Down Expand Up @@ -4114,8 +4120,7 @@ static int snp_handle_ext_guest_req(struct vcpu_svm *svm, gpa_t req_gpa, gpa_t r
return snp_handle_guest_req(svm, req_gpa, resp_gpa);

request_invalid:
ghcb_set_sw_exit_info_1(svm->sev_es.ghcb, GHCB_HV_RESP_MALFORMED_INPUT);
ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, GHCB_ERR_INVALID_INPUT);
svm_vmgexit_bad_input(svm, GHCB_ERR_INVALID_INPUT);
return 1; /* resume guest */
}

Expand Down Expand Up @@ -4307,8 +4312,7 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
if (ret)
return ret;

ghcb_set_sw_exit_info_1(svm->sev_es.ghcb, GHCB_HV_RESP_NO_ACTION);
ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, 0);
svm_vmgexit_success(svm, 0);

exit_code = kvm_ghcb_get_sw_exit_code(control);
switch (exit_code) {
Expand Down Expand Up @@ -4352,21 +4356,19 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
break;
case 1:
/* Get AP jump table address */
ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, sev->ap_jump_table);
svm_vmgexit_success(svm, sev->ap_jump_table);
break;
default:
pr_err("svm: vmgexit: unsupported AP jump table request - exit_info_1=%#llx\n",
control->exit_info_1);
ghcb_set_sw_exit_info_1(svm->sev_es.ghcb, GHCB_HV_RESP_MALFORMED_INPUT);
ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, GHCB_ERR_INVALID_INPUT);
svm_vmgexit_bad_input(svm, GHCB_ERR_INVALID_INPUT);
}

ret = 1;
break;
}
case SVM_VMGEXIT_HV_FEATURES:
ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, GHCB_HV_FT_SUPPORTED);

svm_vmgexit_success(svm, GHCB_HV_FT_SUPPORTED);
ret = 1;
break;
case SVM_VMGEXIT_TERM_REQUEST:
Expand All @@ -4387,8 +4389,7 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
case SVM_VMGEXIT_AP_CREATION:
ret = sev_snp_ap_creation(svm);
if (ret) {
ghcb_set_sw_exit_info_1(svm->sev_es.ghcb, GHCB_HV_RESP_MALFORMED_INPUT);
ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, GHCB_ERR_INVALID_INPUT);
svm_vmgexit_bad_input(svm, GHCB_ERR_INVALID_INPUT);
}

ret = 1;
Expand Down Expand Up @@ -4624,7 +4625,7 @@ void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector)
* Return from an AP Reset Hold VMGEXIT, where the guest will
* set the CS and RIP. Set SW_EXIT_INFO_2 to a non-zero value.
*/
ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, 1);
svm_vmgexit_success(svm, 1);
break;
case AP_RESET_HOLD_MSR_PROTO:
/*
Expand Down
6 changes: 1 addition & 5 deletions arch/x86/kvm/svm/svm.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2973,11 +2973,7 @@ static int svm_complete_emulated_msr(struct kvm_vcpu *vcpu, int err)
if (!err || !sev_es_guest(vcpu->kvm) || WARN_ON_ONCE(!svm->sev_es.ghcb))
return kvm_complete_insn_gp(vcpu, err);

ghcb_set_sw_exit_info_1(svm->sev_es.ghcb, GHCB_HV_RESP_ISSUE_EXCEPTION);
ghcb_set_sw_exit_info_2(svm->sev_es.ghcb,
X86_TRAP_GP |
SVM_EVTINJ_TYPE_EXEPT |
SVM_EVTINJ_VALID);
svm_vmgexit_inject_exception(svm, X86_TRAP_GP);
return 1;
}

Expand Down
29 changes: 29 additions & 0 deletions arch/x86/kvm/svm/svm.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -579,6 +579,35 @@ static inline bool is_vnmi_enabled(struct vcpu_svm *svm)
return false;
}

static inline void svm_vmgexit_set_return_code(struct vcpu_svm *svm,
u64 response, u64 data)
{
ghcb_set_sw_exit_info_1(svm->sev_es.ghcb, response);
ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, data);
}

static inline void svm_vmgexit_inject_exception(struct vcpu_svm *svm, u8 vector)
{
u64 data = SVM_EVTINJ_VALID | SVM_EVTINJ_TYPE_EXEPT | vector;

svm_vmgexit_set_return_code(svm, GHCB_HV_RESP_ISSUE_EXCEPTION, data);
}

static inline void svm_vmgexit_bad_input(struct vcpu_svm *svm, u64 suberror)
{
svm_vmgexit_set_return_code(svm, GHCB_HV_RESP_MALFORMED_INPUT, suberror);
}

static inline void svm_vmgexit_success(struct vcpu_svm *svm, u64 data)
{
svm_vmgexit_set_return_code(svm, GHCB_HV_RESP_NO_ACTION, data);
}

static inline void svm_vmgexit_no_action(struct vcpu_svm *svm, u64 data)
{
svm_vmgexit_set_return_code(svm, GHCB_HV_RESP_NO_ACTION, data);
}

/* svm.c */
#define MSR_INVALID 0xffffffffU

Expand Down

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