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Update the dump_vmcb() routine to output some of the SEV VMSA contents if possible. This can be useful for debug purposes. Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> --- arch/x86/kvm/svm/sev.c | 98 ++++++++++++++++++++++++++++++++++++++++++ arch/x86/kvm/svm/svm.c | 13 ++++++ arch/x86/kvm/svm/svm.h | 11 +++++ 3 files changed, 122 insertions(+) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 661108d65ee7..6e3f5042d9ce 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -563,6 +563,8 @@ static int sev_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp) if (copy_from_user(&params, u64_to_user_ptr(argp->data), sizeof(params))) return -EFAULT; + sev->policy = params.policy; + memset(&start, 0, sizeof(start)); dh_blob = NULL; @@ -2220,6 +2222,8 @@ static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp) if (params.policy & SNP_POLICY_MASK_SINGLE_SOCKET) return -EINVAL; + sev->policy = params.policy; + sev->snp_context = snp_context_create(kvm, argp); if (!sev->snp_context) return -ENOTTY; @@ -4975,3 +4979,97 @@ int sev_private_max_mapping_level(struct kvm *kvm, kvm_pfn_t pfn) return level; } + +struct vmcb_save_area *sev_decrypt_vmsa(struct kvm_vcpu *vcpu) +{ + struct vcpu_svm *svm = to_svm(vcpu); + struct vmcb_save_area *vmsa; + struct kvm_sev_info *sev; + int error = 0; + int ret; + + if (!sev_es_guest(vcpu->kvm)) + return NULL; + + /* + * If the VMSA has not yet been encrypted, return a pointer to the + * current un-encrypted VMSA. + */ + if (!vcpu->arch.guest_state_protected) + return (struct vmcb_save_area *)svm->sev_es.vmsa; + + sev = to_kvm_sev_info(vcpu->kvm); + + /* Check if the SEV policy allows debugging */ + if (sev_snp_guest(vcpu->kvm)) { + if (!(sev->policy & SNP_POLICY_DEBUG)) + return NULL; + } else { + if (sev->policy & SEV_POLICY_NODBG) + return NULL; + } + + if (sev_snp_guest(vcpu->kvm)) { + struct sev_data_snp_dbg dbg = {0}; + + vmsa = snp_alloc_firmware_page(__GFP_ZERO); + if (!vmsa) + return NULL; + + dbg.gctx_paddr = __psp_pa(sev->snp_context); + dbg.src_addr = svm->vmcb->control.vmsa_pa; + dbg.dst_addr = __psp_pa(vmsa); + + ret = sev_issue_cmd(vcpu->kvm, SEV_CMD_SNP_DBG_DECRYPT, &dbg, &error); + + /* + * Return the target page to a hypervisor page no matter what. + * If this fails, the page can't be used, so leak it and don't + * try to use it. + */ + if (snp_page_reclaim(vcpu->kvm, PHYS_PFN(__pa(vmsa)))) + return NULL; + + if (ret) { + pr_err("SEV: SNP_DBG_DECRYPT failed ret=%d, fw_error=%d (%#x)\n", + ret, error, error); + free_page((unsigned long)vmsa); + + return NULL; + } + } else { + struct sev_data_dbg dbg = {0}; + struct page *vmsa_page; + + vmsa_page = alloc_page(GFP_KERNEL); + if (!vmsa_page) + return NULL; + + vmsa = page_address(vmsa_page); + + dbg.handle = sev->handle; + dbg.src_addr = svm->vmcb->control.vmsa_pa; + dbg.dst_addr = __psp_pa(vmsa); + dbg.len = PAGE_SIZE; + + ret = sev_issue_cmd(vcpu->kvm, SEV_CMD_DBG_DECRYPT, &dbg, &error); + if (ret) { + pr_err("SEV: SEV_CMD_DBG_DECRYPT failed ret=%d, fw_error=%d (0x%x)\n", + ret, error, error); + __free_page(vmsa_page); + + return NULL; + } + } + + return vmsa; +} + +void sev_free_decrypted_vmsa(struct kvm_vcpu *vcpu, struct vmcb_save_area *vmsa) +{ + /* If the VMSA has not yet been encrypted, nothing was allocated */ + if (!vcpu->arch.guest_state_protected || !vmsa) + return; + + free_page((unsigned long)vmsa); +} diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index e67de787fc71..21477871073c 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -3423,6 +3423,15 @@ static void dump_vmcb(struct kvm_vcpu *vcpu) pr_err("%-20s%016llx\n", "avic_logical_id:", control->avic_logical_id); pr_err("%-20s%016llx\n", "avic_physical_id:", control->avic_physical_id); pr_err("%-20s%016llx\n", "vmsa_pa:", control->vmsa_pa); + + if (sev_es_guest(vcpu->kvm)) { + save = sev_decrypt_vmsa(vcpu); + if (!save) + goto no_vmsa; + + save01 = save; + } + pr_err("VMCB State Save Area:\n"); pr_err("%-5s s: %04x a: %04x l: %08x b: %016llx\n", "es:", @@ -3493,6 +3502,10 @@ static void dump_vmcb(struct kvm_vcpu *vcpu) pr_err("%-15s %016llx %-13s %016llx\n", "excp_from:", save->last_excp_from, "excp_to:", save->last_excp_to); + +no_vmsa: + if (sev_es_guest(vcpu->kvm)) + sev_free_decrypted_vmsa(vcpu, save); } static bool svm_check_exit_valid(u64 exit_code) diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index ea44c1da5a7c..66979ddc3659 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -98,6 +98,7 @@ struct kvm_sev_info { unsigned int asid; /* ASID used for this guest */ unsigned int handle; /* SEV firmware handle */ int fd; /* SEV device fd */ + unsigned long policy; unsigned long pages_locked; /* Number of pages locked */ struct list_head regions_list; /* List of registered regions */ u64 ap_jump_table; /* SEV-ES AP Jump Table address */ @@ -114,6 +115,9 @@ struct kvm_sev_info { struct mutex guest_req_mutex; /* Must acquire before using bounce buffers */ }; +#define SEV_POLICY_NODBG BIT_ULL(0) +#define SNP_POLICY_DEBUG BIT_ULL(19) + struct kvm_svm { struct kvm kvm; @@ -756,6 +760,8 @@ void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu); int sev_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order); void sev_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end); int sev_private_max_mapping_level(struct kvm *kvm, kvm_pfn_t pfn); +struct vmcb_save_area *sev_decrypt_vmsa(struct kvm_vcpu *vcpu); +void sev_free_decrypted_vmsa(struct kvm_vcpu *vcpu, struct vmcb_save_area *vmsa); #else static inline struct page *snp_safe_alloc_page_node(int node, gfp_t gfp) { @@ -787,6 +793,11 @@ static inline int sev_private_max_mapping_level(struct kvm *kvm, kvm_pfn_t pfn) return 0; } +static inline struct vmcb_save_area *sev_decrypt_vmsa(struct kvm_vcpu *vcpu) +{ + return NULL; +} +static inline void sev_free_decrypted_vmsa(struct kvm_vcpu *vcpu, struct vmcb_save_area *vmsa) {} #endif /* vmenter.S */ -- 2.46.2 </pre></td><td width="32" rowspan="2" class="c" valign="top"><img src="/images/icornerr.gif" width="32" height="32" alt="\" /></td></tr><tr><td align="right" valign="bottom"> 聽 </td></tr><tr><td align="right" valign="bottom">聽</td><td class="c" valign="bottom" style="padding-bottom: 0px"><img src="/images/bcornerl.gif" width="32" height="32" alt="\" /></td><td class="c">聽</td><td class="c" valign="bottom" style="padding-bottom: 0px"><img src="/images/bcornerr.gif" width="32" height="32" alt="/" /></td></tr><tr><td align="right" valign="top" colspan="2"> 聽 </td><td class="lm">Last update: 2025-03-20 14:28 聽聽 [W:0.245 / U:0.026 seconds] 漏2003-2020 <a href="http://blog.jasper.es/">Jasper Spaans</a>|hosted at <a href="https://www.digitalocean.com/?refcode=9a8e99d24cf9">Digital Ocean</a> and my Meterkast|<a href="http://blog.jasper.es/categories.html#lkml-ref">Read the blog</a></td><td>聽</td></tr></table><script language="javascript" src="/js/styleswitcher.js" type="text/javascript"></script></body></html>