commit 1c811d403afd ("x86/sev: Fix position dependent variable
references in startup code") introduced RIP_REL_REF() to force RIP-
relative accesses to global variables, as needed to prevent crashes
during early SEV/SME startup code. For completeness, RIP_REL_REF()
should be used with additional variables during sme_enable() [0].
Access these vars with RIP_REL_REF() to prevent problem reoccurence.

[0] https://lore.kernel.org/all/CAMj1kXHnA0fJu6zh634=fbJswp59kSRAbhW+ubDGj1+NYwZJ-Q@mail.gmail.com/

Fixes: 1c811d403afd ("x86/sev: Fix position dependent variable references in startup code")
Signed-off-by: Kevin Loughlin <kevinloughlin@google.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
---

v1 -> v2: Fix typo in commit message, add Ard's and Tom's "Reviewed-by"

 arch/x86/mm/mem_encrypt_identity.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
index e6c7686f443a..9fce5b87b8c5 100644
--- a/arch/x86/mm/mem_encrypt_identity.c
+++ b/arch/x86/mm/mem_encrypt_identity.c
@@ -565,7 +565,7 @@ void __head sme_enable(struct boot_params *bp)
 	}
 
 	RIP_REL_REF(sme_me_mask) = me_mask;
-	physical_mask &= ~me_mask;
-	cc_vendor = CC_VENDOR_AMD;
+	RIP_REL_REF(physical_mask) &= ~me_mask;
+	RIP_REL_REF(cc_vendor) = CC_VENDOR_AMD;
 	cc_set_mask(me_mask);
 }
-- 
2.47.0.371.ga323438b13-goog

The following commit has been merged into the x86/sev branch of tip:

Commit-ID:     72dafb567760320f2de7447cd6e979bf9d4e5d17
Gitweb:        https://git.kernel.org/tip/72dafb567760320f2de7447cd6e979bf9d4e5d17
Author:        Kevin Loughlin <kevinloughlin@google.com>
AuthorDate:    Fri, 22 Nov 2024 20:23:22 
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Thu, 27 Feb 2025 23:01:33 +01:00

x86/sev: Add missing RIP_REL_REF() invocations during sme_enable()

The following commit:

  1c811d403afd ("x86/sev: Fix position dependent variable references in startup code")

introduced RIP_REL_REF() to force RIP-relative accesses to global variables,
as needed to prevent crashes during early SEV/SME startup code.

For completeness, RIP_REL_REF() should be used with additional variables during
sme_enable():

  https://lore.kernel.org/all/CAMj1kXHnA0fJu6zh634=fbJswp59kSRAbhW+ubDGj1+NYwZJ-Q@mail.gmail.com/

Access these vars with RIP_REL_REF() to prevent problem reoccurence.

Fixes: 1c811d403afd ("x86/sev: Fix position dependent variable references in startup code")
Signed-off-by: Kevin Loughlin <kevinloughlin@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20241122202322.977678-1-kevinloughlin@google.com
---
 arch/x86/mm/mem_encrypt_identity.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
index e6c7686..9fce5b8 100644
--- a/arch/x86/mm/mem_encrypt_identity.c
+++ b/arch/x86/mm/mem_encrypt_identity.c
@@ -565,7 +565,7 @@ void __head sme_enable(struct boot_params *bp)
 	}
 
 	RIP_REL_REF(sme_me_mask) = me_mask;
-	physical_mask &= ~me_mask;
-	cc_vendor = CC_VENDOR_AMD;
+	RIP_REL_REF(physical_mask) &= ~me_mask;
+	RIP_REL_REF(cc_vendor) = CC_VENDOR_AMD;
 	cc_set_mask(me_mask);
 }