[PATCH v3 1/4] x86/sev: Avoid WARN()s in early boot code

From: Ard Biesheuvel
Date: Wed Jun 05 2024 - 06:36:37 EST


From: Ard Biesheuvel <ardb@xxxxxxxxxx>

Using WARN() before the kernel is even mapped 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.

Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
arch/x86/kernel/sev.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 3342ed58e168..33a669e85e5b 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -720,7 +720,7 @@ early_set_pages_state(unsigned long vaddr, unsigned long paddr,
if (op == SNP_PAGE_STATE_SHARED) {
/* Page validation must be rescinded before changing to shared */
ret = pvalidate(vaddr, RMP_PG_SIZE_4K, false);
- if (WARN(ret, "Failed to validate address 0x%lx ret %d", paddr, ret))
+ if (ret)
goto e_term;
}

@@ -733,21 +733,16 @@ 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;

if (op == SNP_PAGE_STATE_PRIVATE) {
/* Page validation must be performed after changing to private */
ret = pvalidate(vaddr, RMP_PG_SIZE_4K, true);
- if (WARN(ret, "Failed to validate address 0x%lx ret %d", paddr, ret))
+ if (ret)
goto e_term;
}

@@ -780,7 +775,7 @@ 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)
{
/*
--
2.45.1.288.g0e0cd299f1-goog