Commit 09d35045 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Ingo Molnar
Browse files

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: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarIngo 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
parent feffde68

arch/x86/coco/sev/core.c

+5 −10
Original line number Diff line number Diff line
@@ -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;

arch/x86/coco/sev/shared.c

+5 −4
Original line number Diff line number Diff line
@@ -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);

	}

}