5.15-stable patches

added patches:
	kvm-x86-use-a-switch-statement-and-macros-in-__feature_translate.patch

diff --git a/queue-5.15/kvm-x86-use-a-switch-statement-and-macros-in-__feature_translate.patch b/queue-5.15/kvm-x86-use-a-switch-statement-and-macros-in-__feature_translate.patch
new file mode 100644 (file)
index 0000000..5cd3e5e
--- /dev/null
+++ b/queue-5.15/kvm-x86-use-a-switch-statement-and-macros-in-__feature_translate.patch
@@ -0,0 +1,87 @@
+From 80c883db87d9ffe2d685e91ba07a087b1c246c78 Mon Sep 17 00:00:00 2001
+From: Jim Mattson <jmattson@google.com>
+Date: Mon, 23 Oct 2023 17:16:36 -0700
+Subject: KVM: x86: Use a switch statement and macros in __feature_translate()
+
+From: Jim Mattson <jmattson@google.com>
+
+commit 80c883db87d9ffe2d685e91ba07a087b1c246c78 upstream.
+
+Use a switch statement with macro-generated case statements to handle
+translating feature flags in order to reduce the probability of runtime
+errors due to copy+paste goofs, to make compile-time errors easier to
+debug, and to make the code more readable.
+
+E.g. the compiler won't directly generate an error for duplicate if
+statements
+
+       if (x86_feature == X86_FEATURE_SGX1)
+               return KVM_X86_FEATURE_SGX1;
+       else if (x86_feature == X86_FEATURE_SGX2)
+               return KVM_X86_FEATURE_SGX1;
+
+and so instead reverse_cpuid_check() will fail due to the untranslated
+entry pointing at a Linux-defined leaf, which provides practically no
+hint as to what is broken
+
+  arch/x86/kvm/reverse_cpuid.h:108:2: error: call to __compiletime_assert_450 declared with 'error' attribute:
+                                      BUILD_BUG_ON failed: x86_leaf == CPUID_LNX_4
+          BUILD_BUG_ON(x86_leaf == CPUID_LNX_4);
+          ^
+whereas duplicate case statements very explicitly point at the offending
+code:
+
+  arch/x86/kvm/reverse_cpuid.h:125:2: error: duplicate case value '361'
+          KVM_X86_TRANSLATE_FEATURE(SGX2);
+          ^
+  arch/x86/kvm/reverse_cpuid.h:124:2: error: duplicate case value '360'
+          KVM_X86_TRANSLATE_FEATURE(SGX1);
+          ^
+
+And without macros, the opposite type of copy+paste goof doesn't generate
+any error at compile-time, e.g. this yields no complaints:
+
+        case X86_FEATURE_SGX1:
+                return KVM_X86_FEATURE_SGX1;
+        case X86_FEATURE_SGX2:
+                return KVM_X86_FEATURE_SGX1;
+
+Note, __feature_translate() is forcibly inlined and the feature is known
+at compile-time, so the code generation between an if-elif sequence and a
+switch statement should be identical.
+
+Signed-off-by: Jim Mattson <jmattson@google.com>
+Link: https://lore.kernel.org/r/20231024001636.890236-2-jmattson@google.com
+[sean: use a macro, rewrite changelog]
+Signed-off-by: Sean Christopherson <seanjc@google.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ arch/x86/kvm/reverse_cpuid.h |   16 +++++++++-------
+ 1 file changed, 9 insertions(+), 7 deletions(-)
+
+--- a/arch/x86/kvm/reverse_cpuid.h
++++ b/arch/x86/kvm/reverse_cpuid.h
+@@ -97,14 +97,16 @@ static __always_inline void reverse_cpui
+  */
+ static __always_inline u32 __feature_translate(int x86_feature)
+ {
+-      if (x86_feature == X86_FEATURE_SGX1)
+-              return KVM_X86_FEATURE_SGX1;
+-      else if (x86_feature == X86_FEATURE_SGX2)
+-              return KVM_X86_FEATURE_SGX2;
+-      else if (x86_feature == X86_FEATURE_RRSBA_CTRL)
+-              return KVM_X86_FEATURE_RRSBA_CTRL;
++#define KVM_X86_TRANSLATE_FEATURE(f)  \
++      case X86_FEATURE_##f: return KVM_X86_FEATURE_##f
+ 
+-      return x86_feature;
++      switch (x86_feature) {
++      KVM_X86_TRANSLATE_FEATURE(SGX1);
++      KVM_X86_TRANSLATE_FEATURE(SGX2);
++      KVM_X86_TRANSLATE_FEATURE(RRSBA_CTRL);
++      default:
++              return x86_feature;
++      }
+ }
+ 
+ static __always_inline u32 __feature_leaf(int x86_feature)

diff --git a/queue-5.15/series b/queue-5.15/series
index 1d6d7b86f16658f2729131395d08dfc6f7283a22..03b1d78bc13d0f5b918a8b3130e83c74de6c7008 100644 (file)
--- a/queue-5.15/series
+++ b/queue-5.15/series
@@ -3,3 +3,4 @@ x86-cpu-support-amd-automatic-ibrs.patch
 x86-bugs-use-sysfs_emit.patch
 kvm-x86-update-kvm-only-leaf-handling-to-allow-for-100-kvm-only-leafs.patch
 kvm-x86-advertise-cpuid.-eax-7-ecx-2-edx-to-userspace.patch
+kvm-x86-use-a-switch-statement-and-macros-in-__feature_translate.patch