diff options
| author | Ard Biesheuvel <ardb@kernel.org> | 2025-08-28 12:22:09 +0200 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2025-09-03 17:58:15 +0200 |
| commit | a5f03880f06a6da6ea5f1d966fffffcb3fc65462 (patch) | |
| tree | c74cbddebdc916a9203060d6f3d824e83d09b99a /arch/x86/boot/compressed | |
| parent | 37dbd78f98a80e89b5413f4649d0fbd023d99b2f (diff) | |
x86/sev: Avoid global variable to store virtual address of SVSM area
The boottime SVSM calling area is used both by the startup code running from
a 1:1 mapping, and potentially later on running from the ordinary kernel
mapping.
This SVSM calling area is statically allocated, and so its physical address
doesn't change. However, its virtual address depends on the calling context
(1:1 mapping or kernel virtual mapping), and even though the variable that
holds the virtual address of this calling area gets updated from 1:1 address
to kernel address during the boot, it is hard to reason about why this is
guaranteed to be safe.
So instead, take the RIP-relative address of the boottime SVSM calling area
whenever its virtual address is required, and only use a global variable for
the physical address.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/20250828102202.1849035-30-ardb+git@google.com
Diffstat (limited to 'arch/x86/boot/compressed')
| -rw-r--r-- | arch/x86/boot/compressed/sev.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c index f197173d60e6..f2b8dfbd453c 100644 --- a/arch/x86/boot/compressed/sev.c +++ b/arch/x86/boot/compressed/sev.c @@ -37,12 +37,12 @@ struct ghcb *boot_ghcb; #define __BOOT_COMPRESSED -extern struct svsm_ca *boot_svsm_caa; extern u64 boot_svsm_caa_pa; struct svsm_ca *svsm_get_caa(void) { - return boot_svsm_caa; + /* The decompressor is mapped 1:1 so VA == PA */ + return (struct svsm_ca *)boot_svsm_caa_pa; } u64 svsm_get_caa_pa(void) @@ -532,7 +532,6 @@ bool early_is_sevsnp_guest(void) /* Obtain the address of the calling area to use */ boot_rdmsr(MSR_SVSM_CAA, &m); - boot_svsm_caa = (void *)m.q; boot_svsm_caa_pa = m.q; /* |