* [PATCH v3] x86emul: add "unblock NMI" retire flag
@ 2017-04-12 15:59 Jan Beulich
2017-04-13 5:59 ` Jan Beulich
0 siblings, 1 reply; 2+ messages in thread
From: Jan Beulich @ 2017-04-12 15:59 UTC (permalink / raw)
To: xen-devel; +Cc: Andrew Cooper, Julien Grall, Paul Durrant
[-- Attachment #1: Type: text/plain, Size: 3074 bytes --]
No matter that we emulate IRET for (guest) real more only right now, we
should get its effect on (virtual) NMI delivery right. Note that we can
simply check the other retire flags also in the !OKAY case, as the
insn emulator now guarantees them to only be set on OKAY.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v3: Drastically simplify the change to _hvm_emulate_one().
v2: Adjust x86_emulate_wrapper() accordingly.
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -1955,9 +1955,6 @@ static int _hvm_emulate_one(struct hvm_e
memcpy(vio->mmio_insn, hvmemul_ctxt->insn_buf, vio->mmio_insn_bytes);
}
- if ( rc != X86EMUL_OKAY )
- return rc;
-
if ( hvmemul_ctxt->ctxt.retire.singlestep )
hvm_inject_hw_exception(TRAP_debug, X86_EVENT_NO_EC);
@@ -1975,6 +1972,10 @@ static int _hvm_emulate_one(struct hvm_e
else
new_intr_shadow &= ~HVM_INTR_SHADOW_STI;
+ /* IRET, if valid in the given context, clears NMI blocking. */
+ if ( hvmemul_ctxt->ctxt.retire.unblock_nmi )
+ new_intr_shadow &= ~HVM_INTR_SHADOW_NMI;
+
if ( hvmemul_ctxt->intr_shadow != new_intr_shadow )
{
hvmemul_ctxt->intr_shadow = new_intr_shadow;
@@ -1987,7 +1988,7 @@ static int _hvm_emulate_one(struct hvm_e
hvm_hlt(regs->eflags);
}
- return X86EMUL_OKAY;
+ return rc;
}
int hvm_emulate_one(
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -4002,6 +4002,7 @@ x86_emulate(
uint32_t mask = X86_EFLAGS_VIP | X86_EFLAGS_VIF | X86_EFLAGS_VM;
fail_if(!in_realmode(ctxt, ops));
+ ctxt->retire.unblock_nmi = true;
if ( (rc = read_ulong(x86_seg_ss, sp_post_inc(op_bytes),
&eip, op_bytes, ctxt, ops)) ||
(rc = read_ulong(x86_seg_ss, sp_post_inc(op_bytes),
@@ -7918,9 +7919,17 @@ int x86_emulate_wrapper(
rc = x86_emulate(ctxt, ops);
- /* Retire flags should only be set for successful instruction emulation. */
+ /*
+ * Most retire flags should only be set for successful instruction
+ * emulation.
+ */
if ( rc != X86EMUL_OKAY )
- ASSERT(ctxt->retire.raw == 0);
+ {
+ typeof(ctxt->retire) retire = ctxt->retire;
+
+ retire.unblock_nmi = false;
+ ASSERT(!retire.raw);
+ }
/* All cases returning X86EMUL_EXCEPTION should have fault semantics. */
if ( rc == X86EMUL_EXCEPTION )
--- a/xen/arch/x86/x86_emulate/x86_emulate.h
+++ b/xen/arch/x86/x86_emulate/x86_emulate.h
@@ -490,6 +490,7 @@ struct x86_emulate_ctxt
bool hlt:1; /* Instruction HLTed. */
bool mov_ss:1; /* Instruction sets MOV-SS irq shadow. */
bool sti:1; /* Instruction sets STI irq shadow. */
+ bool unblock_nmi:1; /* Instruction clears NMI blocking. */
bool singlestep:1; /* Singlestepping was active. */
};
} retire;
[-- Attachment #2: x86emul-unblock-NMI.patch --]
[-- Type: text/plain, Size: 3110 bytes --]
x86emul: add "unblock NMI" retire flag
No matter that we emulate IRET for (guest) real more only right now, we
should get its effect on (virtual) NMI delivery right. Note that we can
simply check the other retire flags also in the !OKAY case, as the
insn emulator now guarantees them to only be set on OKAY.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v3: Drastically simplify the change to _hvm_emulate_one().
v2: Adjust x86_emulate_wrapper() accordingly.
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -1955,9 +1955,6 @@ static int _hvm_emulate_one(struct hvm_e
memcpy(vio->mmio_insn, hvmemul_ctxt->insn_buf, vio->mmio_insn_bytes);
}
- if ( rc != X86EMUL_OKAY )
- return rc;
-
if ( hvmemul_ctxt->ctxt.retire.singlestep )
hvm_inject_hw_exception(TRAP_debug, X86_EVENT_NO_EC);
@@ -1975,6 +1972,10 @@ static int _hvm_emulate_one(struct hvm_e
else
new_intr_shadow &= ~HVM_INTR_SHADOW_STI;
+ /* IRET, if valid in the given context, clears NMI blocking. */
+ if ( hvmemul_ctxt->ctxt.retire.unblock_nmi )
+ new_intr_shadow &= ~HVM_INTR_SHADOW_NMI;
+
if ( hvmemul_ctxt->intr_shadow != new_intr_shadow )
{
hvmemul_ctxt->intr_shadow = new_intr_shadow;
@@ -1987,7 +1988,7 @@ static int _hvm_emulate_one(struct hvm_e
hvm_hlt(regs->eflags);
}
- return X86EMUL_OKAY;
+ return rc;
}
int hvm_emulate_one(
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -4002,6 +4002,7 @@ x86_emulate(
uint32_t mask = X86_EFLAGS_VIP | X86_EFLAGS_VIF | X86_EFLAGS_VM;
fail_if(!in_realmode(ctxt, ops));
+ ctxt->retire.unblock_nmi = true;
if ( (rc = read_ulong(x86_seg_ss, sp_post_inc(op_bytes),
&eip, op_bytes, ctxt, ops)) ||
(rc = read_ulong(x86_seg_ss, sp_post_inc(op_bytes),
@@ -7918,9 +7919,17 @@ int x86_emulate_wrapper(
rc = x86_emulate(ctxt, ops);
- /* Retire flags should only be set for successful instruction emulation. */
+ /*
+ * Most retire flags should only be set for successful instruction
+ * emulation.
+ */
if ( rc != X86EMUL_OKAY )
- ASSERT(ctxt->retire.raw == 0);
+ {
+ typeof(ctxt->retire) retire = ctxt->retire;
+
+ retire.unblock_nmi = false;
+ ASSERT(!retire.raw);
+ }
/* All cases returning X86EMUL_EXCEPTION should have fault semantics. */
if ( rc == X86EMUL_EXCEPTION )
--- a/xen/arch/x86/x86_emulate/x86_emulate.h
+++ b/xen/arch/x86/x86_emulate/x86_emulate.h
@@ -490,6 +490,7 @@ struct x86_emulate_ctxt
bool hlt:1; /* Instruction HLTed. */
bool mov_ss:1; /* Instruction sets MOV-SS irq shadow. */
bool sti:1; /* Instruction sets STI irq shadow. */
+ bool unblock_nmi:1; /* Instruction clears NMI blocking. */
bool singlestep:1; /* Singlestepping was active. */
};
} retire;
[-- Attachment #3: Type: text/plain, Size: 127 bytes --]
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* Re: [PATCH v3] x86emul: add "unblock NMI" retire flag
2017-04-12 15:59 [PATCH v3] x86emul: add "unblock NMI" retire flag Jan Beulich
@ 2017-04-13 5:59 ` Jan Beulich
0 siblings, 0 replies; 2+ messages in thread
From: Jan Beulich @ 2017-04-13 5:59 UTC (permalink / raw)
To: xen-devel; +Cc: Andrew Cooper, Julien Grall, Paul Durrant
>>> On 12.04.17 at 17:59, <JBeulich@suse.com> wrote:
> No matter that we emulate IRET for (guest) real more only right now, we
> should get its effect on (virtual) NMI delivery right. Note that we can
> simply check the other retire flags also in the !OKAY case, as the
> insn emulator now guarantees them to only be set on OKAY.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> ---
> v3: Drastically simplify the change to _hvm_emulate_one().
Please disregard this version - I didn't take care of the RETRY
aspect mentioned in reply to v2; v4 coming.
Jan
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