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-rw-r--r--system/xen/xsa/xsa263-4.10-0001-x86-spec_ctrl-Read-MSR_ARCH_CAPABILITIES-only-once.patch110
1 files changed, 110 insertions, 0 deletions
diff --git a/system/xen/xsa/xsa263-4.10-0001-x86-spec_ctrl-Read-MSR_ARCH_CAPABILITIES-only-once.patch b/system/xen/xsa/xsa263-4.10-0001-x86-spec_ctrl-Read-MSR_ARCH_CAPABILITIES-only-once.patch
new file mode 100644
index 0000000000..c26afebc20
--- /dev/null
+++ b/system/xen/xsa/xsa263-4.10-0001-x86-spec_ctrl-Read-MSR_ARCH_CAPABILITIES-only-once.patch
@@ -0,0 +1,110 @@
+From 13fafdf5c97d3bc2a8851c4d1796feac0f82d498 Mon Sep 17 00:00:00 2001
+From: Andrew Cooper <andrew.cooper3@citrix.com>
+Date: Thu, 26 Apr 2018 12:21:00 +0100
+Subject: [PATCH] x86/spec_ctrl: Read MSR_ARCH_CAPABILITIES only once
+
+Make it available from the beginning of init_speculation_mitigations(), and
+pass it into appropriate functions. Fix an RSBA typo while moving the
+affected comment.
+
+Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
+Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+Reviewed-by: Wei Liu <wei.liu2@citrix.com>
+Reviewed-by: Jan Beulich <jbeulich@suse.com>
+Release-acked-by: Juergen Gross <jgross@suse.com>
+(cherry picked from commit d6c65187252a6c1810fd24c4d46f812840de8d3c)
+---
+ xen/arch/x86/spec_ctrl.c | 34 ++++++++++++++--------------------
+ 1 file changed, 14 insertions(+), 20 deletions(-)
+
+diff --git a/xen/arch/x86/spec_ctrl.c b/xen/arch/x86/spec_ctrl.c
+index fa67a0f..dc90743 100644
+--- a/xen/arch/x86/spec_ctrl.c
++++ b/xen/arch/x86/spec_ctrl.c
+@@ -81,18 +81,15 @@ static int __init parse_bti(const char *s)
+ }
+ custom_param("bti", parse_bti);
+
+-static void __init print_details(enum ind_thunk thunk)
++static void __init print_details(enum ind_thunk thunk, uint64_t caps)
+ {
+ unsigned int _7d0 = 0, e8b = 0, tmp;
+- uint64_t caps = 0;
+
+ /* Collect diagnostics about available mitigations. */
+ if ( boot_cpu_data.cpuid_level >= 7 )
+ cpuid_count(7, 0, &tmp, &tmp, &tmp, &_7d0);
+ if ( boot_cpu_data.extended_cpuid_level >= 0x80000008 )
+ cpuid(0x80000008, &tmp, &e8b, &tmp, &tmp);
+- if ( _7d0 & cpufeat_mask(X86_FEATURE_ARCH_CAPS) )
+- rdmsrl(MSR_ARCH_CAPABILITIES, caps);
+
+ printk(XENLOG_DEBUG "Speculative mitigation facilities:\n");
+
+@@ -125,7 +122,7 @@ static void __init print_details(enum ind_thunk thunk)
+ }
+
+ /* Calculate whether Retpoline is known-safe on this CPU. */
+-static bool __init retpoline_safe(void)
++static bool __init retpoline_safe(uint64_t caps)
+ {
+ unsigned int ucode_rev = this_cpu(ucode_cpu_info).cpu_sig.rev;
+
+@@ -136,19 +133,12 @@ static bool __init retpoline_safe(void)
+ boot_cpu_data.x86 != 6 )
+ return false;
+
+- if ( boot_cpu_has(X86_FEATURE_ARCH_CAPS) )
+- {
+- uint64_t caps;
+-
+- rdmsrl(MSR_ARCH_CAPABILITIES, caps);
+-
+- /*
+- * RBSA may be set by a hypervisor to indicate that we may move to a
+- * processor which isn't retpoline-safe.
+- */
+- if ( caps & ARCH_CAPS_RSBA )
+- return false;
+- }
++ /*
++ * RSBA may be set by a hypervisor to indicate that we may move to a
++ * processor which isn't retpoline-safe.
++ */
++ if ( caps & ARCH_CAPS_RSBA )
++ return false;
+
+ switch ( boot_cpu_data.x86_model )
+ {
+@@ -218,6 +208,10 @@ void __init init_speculation_mitigations(void)
+ {
+ enum ind_thunk thunk = THUNK_DEFAULT;
+ bool ibrs = false;
++ uint64_t caps = 0;
++
++ if ( boot_cpu_has(X86_FEATURE_ARCH_CAPS) )
++ rdmsrl(MSR_ARCH_CAPABILITIES, caps);
+
+ /*
+ * Has the user specified any custom BTI mitigations? If so, follow their
+@@ -246,7 +240,7 @@ void __init init_speculation_mitigations(void)
+ * On Intel hardware, we'd like to use retpoline in preference to
+ * IBRS, but only if it is safe on this hardware.
+ */
+- else if ( retpoline_safe() )
++ else if ( retpoline_safe(caps) )
+ thunk = THUNK_RETPOLINE;
+ else if ( boot_cpu_has(X86_FEATURE_IBRSB) )
+ ibrs = true;
+@@ -331,7 +325,7 @@ void __init init_speculation_mitigations(void)
+ /* (Re)init BSP state now that default_bti_ist_info has been calculated. */
+ init_shadow_spec_ctrl_state();
+
+- print_details(thunk);
++ print_details(thunk, caps);
+ }
+
+ static void __init __maybe_unused build_assertions(void)
+--
+2.1.4
+