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authorDavid Kaplan <david.kaplan@amd.com>2024-06-02 13:19:09 -0500
committerBorislav Petkov (AMD) <bp@alien8.de>2024-06-03 17:19:03 +0200
commit93c1800b3799f17375989b0daf76497dd3e80922 (patch)
treee239ee8c06e170d7fd6d77e488d85a749af2400d /arch
parentc3f38fa61af77b49866b006939479069cd451173 (diff)
x86/kexec: Fix bug with call depth tracking
The call to cc_platform_has() triggers a fault and system crash if call depth tracking is active because the GS segment has been reset by load_segments() and GS_BASE is now 0 but call depth tracking uses per-CPU variables to operate. Call cc_platform_has() earlier in the function when GS is still valid. [ bp: Massage. ] Fixes: 5d8213864ade ("x86/retbleed: Add SKL return thunk") Signed-off-by: David Kaplan <david.kaplan@amd.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Cc: <stable@kernel.org> Link: https://lore.kernel.org/r/20240603083036.637-1-bp@kernel.org
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/machine_kexec_64.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index b180d8e497c3..cc0f7f70b17b 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -295,8 +295,15 @@ void machine_kexec_cleanup(struct kimage *image)
void machine_kexec(struct kimage *image)
{
unsigned long page_list[PAGES_NR];
- void *control_page;
+ unsigned int host_mem_enc_active;
int save_ftrace_enabled;
+ void *control_page;
+
+ /*
+ * This must be done before load_segments() since if call depth tracking
+ * is used then GS must be valid to make any function calls.
+ */
+ host_mem_enc_active = cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT);
#ifdef CONFIG_KEXEC_JUMP
if (image->preserve_context)
@@ -358,7 +365,7 @@ void machine_kexec(struct kimage *image)
(unsigned long)page_list,
image->start,
image->preserve_context,
- cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT));
+ host_mem_enc_active);
#ifdef CONFIG_KEXEC_JUMP
if (image->preserve_context)