diff options
Diffstat (limited to 'system/xen/xsa/xsa263-4.10-0006-x86-spec_ctrl-Elide-MSR_SPEC_CTRL-handling-in-idle-c.patch')
| -rw-r--r-- | system/xen/xsa/xsa263-4.10-0006-x86-spec_ctrl-Elide-MSR_SPEC_CTRL-handling-in-idle-c.patch | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/system/xen/xsa/xsa263-4.10-0006-x86-spec_ctrl-Elide-MSR_SPEC_CTRL-handling-in-idle-c.patch b/system/xen/xsa/xsa263-4.10-0006-x86-spec_ctrl-Elide-MSR_SPEC_CTRL-handling-in-idle-c.patch new file mode 100644 index 0000000000..cbc7fb48d0 --- /dev/null +++ b/system/xen/xsa/xsa263-4.10-0006-x86-spec_ctrl-Elide-MSR_SPEC_CTRL-handling-in-idle-c.patch @@ -0,0 +1,71 @@ +From 811fcf5137abdcd5b9ea7e5212098adb5bedae0f Mon Sep 17 00:00:00 2001 +From: Andrew Cooper <andrew.cooper3@citrix.com> +Date: Mon, 7 May 2018 14:06:16 +0100 +Subject: [PATCH] x86/spec_ctrl: Elide MSR_SPEC_CTRL handling in idle context + when possible + +If Xen is virtualising MSR_SPEC_CTRL handling for guests, but using 0 as its +own MSR_SPEC_CTRL value, spec_ctrl_{enter,exit}_idle() need not write to the +MSR. + +Requested-by: Jan Beulich <JBeulich@suse.com> +Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.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 94df6e8588e35cc2028ccb3fd2921c6e6360605e) +--- + xen/arch/x86/spec_ctrl.c | 4 ++++ + xen/include/asm-x86/cpufeatures.h | 1 + + xen/include/asm-x86/spec_ctrl.h | 4 ++-- + 3 files changed, 7 insertions(+), 2 deletions(-) + +diff --git a/xen/arch/x86/spec_ctrl.c b/xen/arch/x86/spec_ctrl.c +index 015a9e2..55ef79f 100644 +--- a/xen/arch/x86/spec_ctrl.c ++++ b/xen/arch/x86/spec_ctrl.c +@@ -327,6 +327,10 @@ void __init init_speculation_mitigations(void) + /* (Re)init BSP state now that default_spec_ctrl_flags has been calculated. */ + init_shadow_spec_ctrl_state(); + ++ /* If Xen is using any MSR_SPEC_CTRL settings, adjust the idle path. */ ++ if ( default_xen_spec_ctrl ) ++ setup_force_cpu_cap(X86_FEATURE_SC_MSR_IDLE); ++ + print_details(thunk, caps); + } + +diff --git a/xen/include/asm-x86/cpufeatures.h b/xen/include/asm-x86/cpufeatures.h +index f9aa5d7..32b7f04 100644 +--- a/xen/include/asm-x86/cpufeatures.h ++++ b/xen/include/asm-x86/cpufeatures.h +@@ -30,3 +30,4 @@ XEN_CPUFEATURE(SC_MSR, (FSCAPINTS+0)*32+16) /* MSR_SPEC_CTRL used by Xe + XEN_CPUFEATURE(SC_RSB_PV, (FSCAPINTS+0)*32+18) /* RSB overwrite needed for PV */ + XEN_CPUFEATURE(SC_RSB_HVM, (FSCAPINTS+0)*32+19) /* RSB overwrite needed for HVM */ + XEN_CPUFEATURE(NO_XPTI, (FSCAPINTS+0)*32+20) /* XPTI mitigation not in use */ ++XEN_CPUFEATURE(SC_MSR_IDLE, (FSCAPINTS+0)*32+21) /* SC_MSR && default_xen_spec_ctrl */ +diff --git a/xen/include/asm-x86/spec_ctrl.h b/xen/include/asm-x86/spec_ctrl.h +index 7d7c42e..77f92ba 100644 +--- a/xen/include/asm-x86/spec_ctrl.h ++++ b/xen/include/asm-x86/spec_ctrl.h +@@ -52,7 +52,7 @@ static always_inline void spec_ctrl_enter_idle(struct cpu_info *info) + barrier(); + info->spec_ctrl_flags |= SCF_use_shadow; + barrier(); +- asm volatile ( ALTERNATIVE(ASM_NOP3, "wrmsr", X86_FEATURE_SC_MSR) ++ asm volatile ( ALTERNATIVE(ASM_NOP3, "wrmsr", X86_FEATURE_SC_MSR_IDLE) + :: "a" (val), "c" (MSR_SPEC_CTRL), "d" (0) : "memory" ); + } + +@@ -67,7 +67,7 @@ static always_inline void spec_ctrl_exit_idle(struct cpu_info *info) + */ + info->spec_ctrl_flags &= ~SCF_use_shadow; + barrier(); +- asm volatile ( ALTERNATIVE(ASM_NOP3, "wrmsr", X86_FEATURE_SC_MSR) ++ asm volatile ( ALTERNATIVE(ASM_NOP3, "wrmsr", X86_FEATURE_SC_MSR_IDLE) + :: "a" (val), "c" (MSR_SPEC_CTRL), "d" (0) : "memory" ); + } + +-- +2.1.4 + |