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x86/fred: Send an EVENT_CHECK IPI on exit from NMI
Returning from an NMI which hits guest context needs special casing in FRED
mode just like it does in IDT mode.
Break nmi_exit_to_guest() out of handle_ist_exception(), and use it in
entry_FRED_R3() also.
Expand the comment a little, and invert the conditional jump to
compat_restore_all_guest() to avoid needing an #else clause for CONFIG_PV32.
Fixes: 87cfcbe9f0 ("x86/pv: Guest exception handling in FRED mode")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Relase-Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
This commit is contained in:
Andrew Cooper committed
1 parent
00a659a26c
commit
76fc776392
2 files changed
+36
-19
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@@ -20,6 +20,12 @@ FUNC(entry_FRED_R3, 4096)
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GET_STACK_END(14)
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movq STACK_CPUINFO_FIELD(current_vcpu)(%r14), %rbx
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/* NMIs need special handling on return to guest. */
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movzbl UREGS_ss + 6(%rsp), %eax
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and $0xf, %eax
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cmp $X86_ET_NMI, %al
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je nmi_exit_to_guest
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jmp test_all_events
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#else
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BUG /* Not Reached */
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+30
-19
@@ -146,6 +146,35 @@ process_trap:
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jmp test_all_events
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END(switch_to_kernel)
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/*
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* When returning to guest from an NMI, we must execute an IRET/ERETU to
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* re-enable NMIs, and must not process softirqs which can e.g. schedule
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* rather than returning to guest context.
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*
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* If a softirq is pending, send ourselves an EVENT_CHECK IPI to compensate.
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* This will cause softirq processing to occur upon leaving NMI context.
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*
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* %rbx: struct vcpu, %r14 stack_end
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*/
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FUNC(nmi_exit_to_guest)
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mov STACK_CPUINFO_FIELD(processor_id)(%r14), %eax
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shl $IRQSTAT_shift, %eax
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lea irq_stat + IRQSTAT_softirq_pending(%rip), %rcx
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cmpl $0, (%rcx, %rax, 1)
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je 1f
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mov $EVENT_CHECK_VECTOR, %edi
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call send_IPI_self
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1:
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/* For restore_all_guest. */
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mov STACK_CPUINFO_FIELD(current_vcpu)(%r14), %rbx
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#ifdef CONFIG_PV32
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mov VCPU_domain(%rbx), %rax
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cmpb $0, DOMAIN_is_32bit_pv(%rax)
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jne compat_restore_all_guest
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#endif
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jmp restore_all_guest
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END(nmi_exit_to_guest)
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.section .text.entry, "ax", @progbits
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/* %rbx: struct vcpu, interrupts disabled */
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@@ -1209,25 +1238,7 @@ FUNC(handle_ist_exception)
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#ifdef CONFIG_PV
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testb $3,UREGS_cs(%rsp)
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jz restore_all_xen
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/* Send an IPI to ourselves to cover for the lack of event checking. */
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mov STACK_CPUINFO_FIELD(processor_id)(%r14), %eax
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shll $IRQSTAT_shift,%eax
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leaq irq_stat+IRQSTAT_softirq_pending(%rip),%rcx
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cmpl $0,(%rcx,%rax,1)
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je 1f
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movl $EVENT_CHECK_VECTOR,%edi
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call send_IPI_self
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1:
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/* For restore_all_guest. */
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mov STACK_CPUINFO_FIELD(current_vcpu)(%r14), %rbx
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#ifdef CONFIG_PV32
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movq VCPU_domain(%rbx),%rax
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cmpb $0,DOMAIN_is_32bit_pv(%rax)
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je restore_all_guest
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jmp compat_restore_all_guest
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#else
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jmp restore_all_guest
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#endif
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jmp nmi_exit_to_guest
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#else
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ASSERT_CONTEXT_IS_XEN
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jmp restore_all_xen
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