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[RFT,v3,02/21] x86/sev: Use MSR protocol for remapping SVSM calling area

Message ID 20250512190834.332684-25-ardb+git@google.com
State New
Headers show
Series x86: strict separation of startup code | expand

Commit Message

Ard Biesheuvel May 12, 2025, 7:08 p.m. UTC 
From: Ard Biesheuvel <ardb@kernel.org>

As the preceding code comment already indicates, remapping the SVSM
calling area occurs long before the GHCB page is configured, and so
calling svsm_perform_call_protocol() is guaranteed to result in a call
to svsm_perform_msr_protocol().

So just call the latter directly. This allows most of the GHCB based API
infrastructure to be moved out of the startup code in a subsequent
patch.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/x86/boot/startup/sev-startup.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
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Patch

diff --git a/arch/x86/boot/startup/sev-startup.c b/arch/x86/boot/startup/sev-startup.c
index 435853a55768..a1d5a5632d58 100644
--- a/arch/x86/boot/startup/sev-startup.c
+++ b/arch/x86/boot/startup/sev-startup.c
@@ -325,7 +325,9 @@  static __head void svsm_setup(struct cc_blob_sev_info *cc_info)
 	call.caa = svsm_get_caa();
 	call.rax = SVSM_CORE_CALL(SVSM_CORE_REMAP_CA);
 	call.rcx = pa;
-	ret = svsm_perform_call_protocol(&call);
+	do {
+		ret = svsm_perform_msr_protocol(&call);
+	} while (ret == -EAGAIN);
 	if (ret)
 		sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_SVSM_CA_REMAP_FAIL);