diff options
Diffstat (limited to 'arch/x86/kernel/sev-shared.c')
| -rw-r--r-- | arch/x86/kernel/sev-shared.c | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index 3a5b0c9c4fcc..2eabccde94fb 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -12,6 +12,9 @@ #ifndef __BOOT_COMPRESSED #define error(v) pr_err(v) #define has_cpuflag(f) boot_cpu_has(f) +#else +#undef WARN +#define WARN(condition, format...) (!!(condition)) #endif /* I/O parameters for CPUID-related helpers */ @@ -991,3 +994,103 @@ static void __init setup_cpuid_table(const struct cc_blob_sev_info *cc_info) cpuid_ext_range_max = fn->eax; } } + +static void pvalidate_pages(struct snp_psc_desc *desc) +{ + struct psc_entry *e; + unsigned long vaddr; + unsigned int size; + unsigned int i; + bool validate; + int rc; + + for (i = 0; i <= desc->hdr.end_entry; i++) { + e = &desc->entries[i]; + + vaddr = (unsigned long)pfn_to_kaddr(e->gfn); + size = e->pagesize ? RMP_PG_SIZE_2M : RMP_PG_SIZE_4K; + validate = e->operation == SNP_PAGE_STATE_PRIVATE; + + rc = pvalidate(vaddr, size, validate); + if (rc == PVALIDATE_FAIL_SIZEMISMATCH && size == RMP_PG_SIZE_2M) { + unsigned long vaddr_end = vaddr + PMD_SIZE; + + for (; vaddr < vaddr_end; vaddr += PAGE_SIZE) { + rc = pvalidate(vaddr, RMP_PG_SIZE_4K, validate); + if (rc) + break; + } + } + + if (rc) { + WARN(1, "Failed to validate address 0x%lx ret %d", vaddr, rc); + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PVALIDATE); + } + } +} + +static int vmgexit_psc(struct ghcb *ghcb, struct snp_psc_desc *desc) +{ + int cur_entry, end_entry, ret = 0; + struct snp_psc_desc *data; + struct es_em_ctxt ctxt; + + vc_ghcb_invalidate(ghcb); + + /* Copy the input desc into GHCB shared buffer */ + data = (struct snp_psc_desc *)ghcb->shared_buffer; + memcpy(ghcb->shared_buffer, desc, min_t(int, GHCB_SHARED_BUF_SIZE, sizeof(*desc))); + + /* + * As per the GHCB specification, the hypervisor can resume the guest + * before processing all the entries. Check whether all the entries + * are processed. If not, then keep retrying. Note, the hypervisor + * will update the data memory directly to indicate the status, so + * reference the data->hdr everywhere. + * + * The strategy here is to wait for the hypervisor to change the page + * state in the RMP table before guest accesses the memory pages. If the + * page state change was not successful, then later memory access will + * result in a crash. + */ + cur_entry = data->hdr.cur_entry; + end_entry = data->hdr.end_entry; + + while (data->hdr.cur_entry <= data->hdr.end_entry) { + ghcb_set_sw_scratch(ghcb, (u64)__pa(data)); + + /* This will advance the shared buffer data points to. */ + ret = sev_es_ghcb_hv_call(ghcb, &ctxt, SVM_VMGEXIT_PSC, 0, 0); + + /* + * Page State Change VMGEXIT can pass error code through + * exit_info_2. + */ + if (WARN(ret || ghcb->save.sw_exit_info_2, + "SNP: PSC failed ret=%d exit_info_2=%llx\n", + ret, ghcb->save.sw_exit_info_2)) { + ret = 1; + goto out; + } + + /* Verify that reserved bit is not set */ + if (WARN(data->hdr.reserved, "Reserved bit is set in the PSC header\n")) { + ret = 1; + goto out; + } + + /* + * Sanity check that entry processing is not going backwards. + * This will happen only if hypervisor is tricking us. + */ + if (WARN(data->hdr.end_entry > end_entry || cur_entry > data->hdr.cur_entry, +"SNP: PSC processing going backward, end_entry %d (got %d) cur_entry %d (got %d)\n", + end_entry, data->hdr.end_entry, cur_entry, data->hdr.cur_entry)) { + ret = 1; + goto out; + } + } + +out: + return ret; +} |