Re: [Xen-devel] [PATCH v4 7/8] x86: also NOP out xen_cr3 restores of XPTI

2018-03-22 Thread Wei Liu 
On Mon, Mar 19, 2018 at 07:41:11AM -0600, Jan Beulich wrote:
> ... despite quite likely the gain being rather limited.
> 
> Signed-off-by: Jan Beulich 

Reviewed-by: Wei Liu 

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Re: [Xen-devel] [PATCH v4 7/8] x86: also NOP out xen_cr3 restores of XPTI

2018-03-21 Thread Juergen Gross 
On 19/03/18 14:41, Jan Beulich wrote:
> ... despite quite likely the gain being rather limited.
> 
> Signed-off-by: Jan Beulich 

Tested-by: Juergen Gross 
Reviewed-by: Juergen Gross 


Juergen

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[Xen-devel] [PATCH v4 7/8] x86: also NOP out xen_cr3 restores of XPTI

2018-03-19 Thread Jan Beulich 
... despite quite likely the gain being rather limited.

Signed-off-by: Jan Beulich 
---
v4: Split off from earlier patch.

--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -583,7 +583,8 @@ ENTRY(common_interrupt)
 CR4_PV32_RESTORE
 movq %rsp,%rdi
 callq do_IRQ
-mov   %r15, STACK_CPUINFO_FIELD(xen_cr3)(%r14)
+ALTERNATIVE __stringify(mov %r15, STACK_CPUINFO_FIELD(xen_cr3)(%r14)), 
\
+"", X86_FEATURE_NO_XPTI
 jmp ret_from_intr
 
 ENTRY(page_fault)
@@ -665,7 +666,8 @@ handle_exception_saved:
 PERFC_INCR(exceptions, %rax, %rbx)
 mov   (%rdx, %rax, 8), %rdx
 INDIRECT_CALL %rdx
-mov   %r15, STACK_CPUINFO_FIELD(xen_cr3)(%r14)
+ALTERNATIVE __stringify(mov %r15, STACK_CPUINFO_FIELD(xen_cr3)(%r14)), 
\
+"", X86_FEATURE_NO_XPTI
 testb $3,UREGS_cs(%rsp)
 jzrestore_all_xen
 leaq  VCPU_trap_bounce(%rbx),%rdx
@@ -698,7 +700,8 @@ exception_with_ints_disabled:
 rep;  movsq # make room for ec/ev
 1:  movq  UREGS_error_code(%rsp),%rax # ec/ev
 movq  %rax,UREGS_kernel_sizeof(%rsp)
-mov   %r15, STACK_CPUINFO_FIELD(xen_cr3)(%r14)
+ALTERNATIVE __stringify(mov %r15, STACK_CPUINFO_FIELD(xen_cr3)(%r14)), 
\
+"", X86_FEATURE_NO_XPTI
 jmp   restore_all_xen   # return to fixup code
 
 /* No special register assumptions. */
@@ -849,7 +852,8 @@ handle_ist_exception:
 leaq  exception_table(%rip),%rdx
 mov   (%rdx, %rax, 8), %rdx
 INDIRECT_CALL %rdx
-mov   %r15, STACK_CPUINFO_FIELD(xen_cr3)(%r14)
+ALTERNATIVE __stringify(mov %r15, STACK_CPUINFO_FIELD(xen_cr3)(%r14)), 
\
+"", X86_FEATURE_NO_XPTI
 cmpb  $TRAP_nmi,UREGS_entry_vector(%rsp)
 jne   ret_from_intr
 




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