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x86/spec-ctrl: Simplify DO_COND_IBPB
With the prior refactoring, SPEC_CTRL_ENTRY_{PV,INTR} both load SCF into %ebx,
and handle the conditional safety including skipping if interrupting Xen.
Therefore, we can drop the maybexen parameter and the conditional safety.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
(cherry picked from commit 2378d16a93)
This commit is contained in:
Andrew Cooper committed
1 parent
6107fa0187
commit
7efe5a0eee
1 file changed
+8
-22
@@ -87,33 +87,21 @@
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* - SPEC_CTRL_EXIT_TO_{SVM,VMX}
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*/
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.macro DO_SPEC_CTRL_COND_IBPB maybexen:req
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.macro DO_COND_IBPB
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/*
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* Requires %rsp=regs (also cpuinfo if !maybexen)
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* Requires %r14=stack_end (if maybexen), %rdx=0
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* Clobbers %rax, %rcx, %rdx
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* Requires %rbx=SCF, %rdx=0
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* Clobbers %rax, %rcx
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*
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* Conditionally issue IBPB if SCF_entry_ibpb is active. In the maybexen
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* case, we can safely look at UREGS_cs to skip taking the hit when
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* interrupting Xen.
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* Conditionally issue IBPB if SCF_entry_ibpb is active.
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*/
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.if \maybexen
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testb $SCF_entry_ibpb, STACK_CPUINFO_FIELD(scf)(%r14)
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jz .L\@_skip
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testb $3, UREGS_cs(%rsp)
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.else
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testb $SCF_entry_ibpb, CPUINFO_scf(%rsp)
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.endif
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testb $SCF_entry_ibpb, %bl
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jz .L\@_skip
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mov $MSR_PRED_CMD, %ecx
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mov $PRED_CMD_IBPB, %eax
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wrmsr
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jmp .L\@_done
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.L\@_skip:
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lfence
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.L\@_done:
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.endm
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.macro DO_OVERWRITE_RSB tmp=rax xu
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@@ -273,8 +261,7 @@
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*/
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movzbl STACK_CPUINFO_FIELD(scf)(%r14), %ebx
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ALTERNATIVE "", __stringify(DO_SPEC_CTRL_COND_IBPB maybexen=0), \
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X86_FEATURE_IBPB_ENTRY_PV
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ALTERNATIVE "", DO_COND_IBPB, X86_FEATURE_IBPB_ENTRY_PV
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ALTERNATIVE "", DO_OVERWRITE_RSB, X86_FEATURE_SC_RSB_PV
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@@ -303,8 +290,7 @@
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testb $3, UREGS_cs(%rsp)
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jz .L\@_skip
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ALTERNATIVE "", __stringify(DO_SPEC_CTRL_COND_IBPB maybexen=1), \
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X86_FEATURE_IBPB_ENTRY_PV
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ALTERNATIVE "", DO_COND_IBPB, X86_FEATURE_IBPB_ENTRY_PV
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ALTERNATIVE "", DO_OVERWRITE_RSB, X86_FEATURE_SC_RSB_PV
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@@ -344,7 +330,7 @@
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* Clobbers %rax, %rbx, %rcx, %rdx
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*
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* This is logical merge of:
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* DO_SPEC_CTRL_COND_IBPB maybexen=0
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* DO_COND_IBPB
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* DO_OVERWRITE_RSB
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* DO_SPEC_CTRL_ENTRY maybexen=1
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* but with conditionals rather than alternatives.
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