From ea08eeccae9297f7aabd2ef7f0c2517ac4549acc Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:18:26 +0000
Subject: [PATCH] write in 30M
---
kernel/arch/x86/include/asm/virtext.h | 22 +++++++++++++++-------
1 files changed, 15 insertions(+), 7 deletions(-)
diff --git a/kernel/arch/x86/include/asm/virtext.h b/kernel/arch/x86/include/asm/virtext.h
index fda3e77..3314742 100644
--- a/kernel/arch/x86/include/asm/virtext.h
+++ b/kernel/arch/x86/include/asm/virtext.h
@@ -95,12 +95,6 @@
return 0;
}
- if (boot_cpu_data.extended_cpuid_level < SVM_CPUID_FUNC) {
- if (msg)
- *msg = "can't execute cpuid_8000000a";
- return 0;
- }
-
if (!boot_cpu_has(X86_FEATURE_SVM)) {
if (msg)
*msg = "svm not available";
@@ -120,7 +114,21 @@
wrmsrl(MSR_VM_HSAVE_PA, 0);
rdmsrl(MSR_EFER, efer);
- wrmsrl(MSR_EFER, efer & ~EFER_SVME);
+ if (efer & EFER_SVME) {
+ /*
+ * Force GIF=1 prior to disabling SVM to ensure INIT and NMI
+ * aren't blocked, e.g. if a fatal error occurred between CLGI
+ * and STGI. Note, STGI may #UD if SVM is disabled from NMI
+ * context between reading EFER and executing STGI. In that
+ * case, GIF must already be set, otherwise the NMI would have
+ * been blocked, so just eat the fault.
+ */
+ asm_volatile_goto("1: stgi\n\t"
+ _ASM_EXTABLE(1b, %l[fault])
+ ::: "memory" : fault);
+fault:
+ wrmsrl(MSR_EFER, efer & ~EFER_SVME);
+ }
}
/** Makes sure SVM is disabled, if it is supported on the CPU
--
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