x86/sev: Avoid WARN()s and panic()s in early boot code

Using WARN() or panic() while executing from the early 1:1 mapping is
unlikely to do anything useful: the string literals are passed using
their kernel virtual addresses which are not even mapped yet. But even
if they were, calling into the printk() machinery from the early 1:1
mapped code is not going to get very far.

So drop the WARN()s entirely, and replace panic() with a deadloop.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: https://lore.kernel.org/r/20241205112804.3416920-10-ardb+git@google.com

diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index c5b0148b8c0a191f5aa38af73a52c77d6bba3e2d..499b41953e3cd429e3943d801ab1ed57d3085b79 100644 (file)
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -777,15 +777,10 @@ early_set_pages_state(unsigned long vaddr, unsigned long paddr,
 
                val = sev_es_rd_ghcb_msr();
 
-               if (WARN(GHCB_RESP_CODE(val) != GHCB_MSR_PSC_RESP,
-                        "Wrong PSC response code: 0x%x\n",
-                        (unsigned int)GHCB_RESP_CODE(val)))
+               if (GHCB_RESP_CODE(val) != GHCB_MSR_PSC_RESP)
                        goto e_term;
 
-               if (WARN(GHCB_MSR_PSC_RESP_VAL(val),
-                        "Failed to change page state to '%s' paddr 0x%lx error 0x%llx\n",
-                        op == SNP_PAGE_STATE_PRIVATE ? "private" : "shared",
-                        paddr, GHCB_MSR_PSC_RESP_VAL(val)))
+               if (GHCB_MSR_PSC_RESP_VAL(val))
                        goto e_term;
 
                /* Page validation must be performed after changing to private */
@@ -821,7 +816,7 @@ void __head early_snp_set_memory_private(unsigned long vaddr, unsigned long padd
        early_set_pages_state(vaddr, paddr, npages, SNP_PAGE_STATE_PRIVATE);
 }
 
-void __init early_snp_set_memory_shared(unsigned long vaddr, unsigned long paddr,
+void __head early_snp_set_memory_shared(unsigned long vaddr, unsigned long paddr,
                                        unsigned long npages)
 {
        /*
@@ -2361,8 +2356,8 @@ static __head void svsm_setup(struct cc_blob_sev_info *cc_info)
        call.rax = SVSM_CORE_CALL(SVSM_CORE_REMAP_CA);
        call.rcx = pa;
        ret = svsm_perform_call_protocol(&call);
-       if (ret)
-               panic("Can't remap the SVSM CA, ret=%d, rax_out=0x%llx\n", ret, call.rax_out);
+       while (ret)
+               cpu_relax(); /* too early to panic */
 
        RIP_REL_REF(boot_svsm_caa) = (struct svsm_ca *)pa;
        RIP_REL_REF(boot_svsm_caa_pa) = pa;

diff --git a/arch/x86/coco/sev/shared.c b/arch/x86/coco/sev/shared.c
index 71de5319408910b251930eb1fb3598b3fb605d93..afb7ffc355fee372c3b6eb8f015b917649972ec1 100644 (file)
--- a/arch/x86/coco/sev/shared.c
+++ b/arch/x86/coco/sev/shared.c
@@ -1243,7 +1243,7 @@ static void svsm_pval_terminate(struct svsm_pvalidate_call *pc, int ret, u64 svs
        __pval_terminate(pfn, action, page_size, ret, svsm_ret);
 }
 
-static void svsm_pval_4k_page(unsigned long paddr, bool validate)
+static void __head svsm_pval_4k_page(unsigned long paddr, bool validate)
 {
        struct svsm_pvalidate_call *pc;
        struct svsm_call call = {};
@@ -1275,12 +1275,13 @@ static void svsm_pval_4k_page(unsigned long paddr, bool validate)
 
        ret = svsm_perform_call_protocol(&call);
        if (ret)
-               svsm_pval_terminate(pc, ret, call.rax_out);
+               sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PVALIDATE);
 
        native_local_irq_restore(flags);
 }
 
-static void pvalidate_4k_page(unsigned long vaddr, unsigned long paddr, bool validate)
+static void __head pvalidate_4k_page(unsigned long vaddr, unsigned long paddr,
+                                    bool validate)
 {
        int ret;
 
@@ -1293,7 +1294,7 @@ static void pvalidate_4k_page(unsigned long vaddr, unsigned long paddr, bool val
        } else {
                ret = pvalidate(vaddr, RMP_PG_SIZE_4K, validate);
                if (ret)
-                       __pval_terminate(PHYS_PFN(paddr), validate, RMP_PG_SIZE_4K, ret, 0);
+                       sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PVALIDATE);
        }
 }