* [PATCH RESEND] kvm/x86: propagate fetch fault into guest
@ 2018-09-18 23:03 Peng Hao
2018-09-19 14:33 ` Sean Christopherson
0 siblings, 1 reply; 4+ messages in thread
From: Peng Hao @ 2018-09-18 23:03 UTC (permalink / raw)
To: pbonzini, rkrcmar, tglx, mingo, hpa
Cc: linux-kernel, kvm, x86, peng.hao2, Peng Hao
From: Peng Hao <peng.hao2@zte.com.cn>
When handling ept misconfig exit, it will call emulate instruction
with insn_len = 0. The decode instruction function may return a fetch
fault and should propagate to guest.
The problem will result to emulation fail.
KVM internal error. Suberror: 1
emulation failure
EAX=f81a0024 EBX=f6a07000 ECX=f6a0737c EDX=f8be0118
ESI=f6a0737c EDI=00000021 EBP=f6929f98 ESP=f6929f98
EIP=f8bdd141 EFL=00010086 [--S--P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =007b 00000000 ffffffff 00c0f300 DPL=3 DS [-WA]
CS =0060 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA]
SS =0068 00000000 ffffffff 00c09300 DPL=0 DS [-WA]
DS =007b 00000000 ffffffff 00c0f300 DPL=3 DS [-WA]
FS =00d8 2c044000 ffffffff 00809300 DPL=0 DS16 [-WA]
GS =0033 081a44c8 01000fff 00d0f300 DPL=3 DS [-WA]
LDT=0000 00000000 ffffffff 00000000
TR =0080 f6ea0c80 0000206b 00008b00 DPL=0 TSS32-busy
GDT= f6e99000 000000ff
IDT= fffbb000 000007ff
CR0=80050033 CR2=b757d000 CR3=35d31000 CR4=001406d0
Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
---
arch/x86/kvm/emulate.c | 5 ++++-
arch/x86/kvm/x86.c | 4 +++-
2 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 106482d..aecf9a72 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -5105,8 +5105,11 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
memcpy(ctxt->fetch.data, insn, insn_len);
else {
rc = __do_insn_fetch_bytes(ctxt, 1);
- if (rc != X86EMUL_CONTINUE)
+ if (rc != X86EMUL_CONTINUE) {
+ if (rc == X86EMUL_PROPAGATE_FAULT)
+ ctxt->have_exception = true;
return rc;
+ }
}
switch (mode) {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 542f631..27072e1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6188,8 +6188,10 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
if (reexecute_instruction(vcpu, cr2, write_fault_to_spt,
emulation_type))
return EMULATE_DONE;
- if (ctxt->have_exception && inject_emulated_exception(vcpu))
+ if (ctxt->have_exception) {
+ inject_emulated_exception(vcpu);
return EMULATE_DONE;
+ }
if (emulation_type & EMULTYPE_SKIP)
return EMULATE_FAIL;
return handle_emulation_failure(vcpu, emulation_type);
--
1.8.3.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH RESEND] kvm/x86: propagate fetch fault into guest
2018-09-18 23:03 [PATCH RESEND] kvm/x86: propagate fetch fault into guest Peng Hao
@ 2018-09-19 14:33 ` Sean Christopherson
2018-09-20 16:32 ` Paolo Bonzini
0 siblings, 1 reply; 4+ messages in thread
From: Sean Christopherson @ 2018-09-19 14:33 UTC (permalink / raw)
To: Peng Hao, pbonzini, rkrcmar, tglx, mingo, hpa
Cc: linux-kernel, kvm, x86, peng.hao2, Peng Hao
On Tue, 2018-09-18 at 19:03 -0400, Peng Hao wrote:
> From: Peng Hao <peng.hao2@zte.com.cn>
>
> When handling ept misconfig exit, it will call emulate instruction
> with insn_len = 0. The decode instruction function may return a fetch
> fault and should propagate to guest.
What fault is encountered, e.g. #PF, #UD, etc...? Something like a
#UD at this point should result in an exit to userspace as it means
KVM was unable to emulate an instruction that was successfully
decoded by hardware.
> The problem will result to emulation fail.
> KVM internal error. Suberror: 1
> emulation failure
> EAX=f81a0024 EBX=f6a07000 ECX=f6a0737c EDX=f8be0118
> ESI=f6a0737c EDI=00000021 EBP=f6929f98 ESP=f6929f98
> EIP=f8bdd141 EFL=00010086 [--S--P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
> ES =007b 00000000 ffffffff 00c0f300 DPL=3 DS [-WA]
> CS =0060 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA]
> SS =0068 00000000 ffffffff 00c09300 DPL=0 DS [-WA]
> DS =007b 00000000 ffffffff 00c0f300 DPL=3 DS [-WA]
> FS =00d8 2c044000 ffffffff 00809300 DPL=0 DS16 [-WA]
> GS =0033 081a44c8 01000fff 00d0f300 DPL=3 DS [-WA]
> LDT=0000 00000000 ffffffff 00000000
> TR =0080 f6ea0c80 0000206b 00008b00 DPL=0 TSS32-busy
> GDT= f6e99000 000000ff
> IDT= fffbb000 000007ff
> CR0=80050033 CR2=b757d000 CR3=35d31000 CR4=001406d0
>
> Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
> Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
> ---
> arch/x86/kvm/emulate.c | 5 ++++-
> arch/x86/kvm/x86.c | 4 +++-
> 2 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index 106482d..aecf9a72 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -5105,8 +5105,11 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
> memcpy(ctxt->fetch.data, insn, insn_len);
> else {
> rc = __do_insn_fetch_bytes(ctxt, 1);
> - if (rc != X86EMUL_CONTINUE)
> + if (rc != X86EMUL_CONTINUE) {
> + if (rc == X86EMUL_PROPAGATE_FAULT)
> + ctxt->have_exception = true;
> return rc;
> + }
> }
>
> switch (mode) {
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 542f631..27072e1 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6188,8 +6188,10 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
> if (reexecute_instruction(vcpu, cr2, write_fault_to_spt,
> emulation_type))
> return EMULATE_DONE;
> - if (ctxt->have_exception && inject_emulated_exception(vcpu))
> + if (ctxt->have_exception) {
> + inject_emulated_exception(vcpu);
> return EMULATE_DONE;
> + }
> if (emulation_type & EMULTYPE_SKIP)
> return EMULATE_FAIL;
> return handle_emulation_failure(vcpu, emulation_type);
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH RESEND] kvm/x86: propagate fetch fault into guest
2018-09-19 14:33 ` Sean Christopherson
@ 2018-09-20 16:32 ` Paolo Bonzini
2018-09-20 17:42 ` Sean Christopherson
0 siblings, 1 reply; 4+ messages in thread
From: Paolo Bonzini @ 2018-09-20 16:32 UTC (permalink / raw)
To: Sean Christopherson, Peng Hao, rkrcmar, tglx, mingo, hpa
Cc: linux-kernel, kvm, x86, peng.hao2, Peng Hao
On 19/09/2018 16:33, Sean Christopherson wrote:
> On Tue, 2018-09-18 at 19:03 -0400, Peng Hao wrote:
>> From: Peng Hao <peng.hao2@zte.com.cn>
>>
>> When handling ept misconfig exit, it will call emulate instruction
>> with insn_len = 0. The decode instruction function may return a fetch
>> fault and should propagate to guest.
>
> What fault is encountered, e.g. #PF, #UD, etc...? Something like a
> #UD at this point should result in an exit to userspace as it means
> KVM was unable to emulate an instruction that was successfully
> decoded by hardware.
If it's the same bug as https://lore.kernel.org/patchwork/patch/850077/
it would be a #PF.
Paolo
>> The problem will result to emulation fail.
>> KVM internal error. Suberror: 1
>> emulation failure
>> EAX=f81a0024 EBX=f6a07000 ECX=f6a0737c EDX=f8be0118
>> ESI=f6a0737c EDI=00000021 EBP=f6929f98 ESP=f6929f98
>> EIP=f8bdd141 EFL=00010086 [--S--P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
>> ES =007b 00000000 ffffffff 00c0f300 DPL=3 DS [-WA]
>> CS =0060 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA]
>> SS =0068 00000000 ffffffff 00c09300 DPL=0 DS [-WA]
>> DS =007b 00000000 ffffffff 00c0f300 DPL=3 DS [-WA]
>> FS =00d8 2c044000 ffffffff 00809300 DPL=0 DS16 [-WA]
>> GS =0033 081a44c8 01000fff 00d0f300 DPL=3 DS [-WA]
>> LDT=0000 00000000 ffffffff 00000000
>> TR =0080 f6ea0c80 0000206b 00008b00 DPL=0 TSS32-busy
>> GDT= f6e99000 000000ff
>> IDT= fffbb000 000007ff
>> CR0=80050033 CR2=b757d000 CR3=35d31000 CR4=001406d0
>>
>> Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
>> Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
>> ---
>> arch/x86/kvm/emulate.c | 5 ++++-
>> arch/x86/kvm/x86.c | 4 +++-
>> 2 files changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
>> index 106482d..aecf9a72 100644
>> --- a/arch/x86/kvm/emulate.c
>> +++ b/arch/x86/kvm/emulate.c
>> @@ -5105,8 +5105,11 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
>> memcpy(ctxt->fetch.data, insn, insn_len);
>> else {
>> rc = __do_insn_fetch_bytes(ctxt, 1);
>> - if (rc != X86EMUL_CONTINUE)
>> + if (rc != X86EMUL_CONTINUE) {
>> + if (rc == X86EMUL_PROPAGATE_FAULT)
>> + ctxt->have_exception = true;
>> return rc;
>> + }
>> }
>>
>> switch (mode) {
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 542f631..27072e1 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -6188,8 +6188,10 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
>> if (reexecute_instruction(vcpu, cr2, write_fault_to_spt,
>> emulation_type))
>> return EMULATE_DONE;
>> - if (ctxt->have_exception && inject_emulated_exception(vcpu))
>> + if (ctxt->have_exception) {
>> + inject_emulated_exception(vcpu);
>> return EMULATE_DONE;
>> + }
>> if (emulation_type & EMULTYPE_SKIP)
>> return EMULATE_FAIL;
>> return handle_emulation_failure(vcpu, emulation_type);
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH RESEND] kvm/x86: propagate fetch fault into guest
2018-09-20 16:32 ` Paolo Bonzini
@ 2018-09-20 17:42 ` Sean Christopherson
0 siblings, 0 replies; 4+ messages in thread
From: Sean Christopherson @ 2018-09-20 17:42 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Peng Hao, rkrcmar, tglx, mingo, hpa, linux-kernel, kvm, x86,
peng.hao2, Peng Hao
On Thu, Sep 20, 2018 at 06:32:10PM +0200, Paolo Bonzini wrote:
> On 19/09/2018 16:33, Sean Christopherson wrote:
> > On Tue, 2018-09-18 at 19:03 -0400, Peng Hao wrote:
> >> From: Peng Hao <peng.hao2@zte.com.cn>
> >>
> >> When handling ept misconfig exit, it will call emulate instruction
> >> with insn_len = 0. The decode instruction function may return a fetch
> >> fault and should propagate to guest.
> >
> > What fault is encountered, e.g. #PF, #UD, etc...? Something like a
> > #UD at this point should result in an exit to userspace as it means
> > KVM was unable to emulate an instruction that was successfully
> > decoded by hardware.
>
> If it's the same bug as https://lore.kernel.org/patchwork/patch/850077/
> it would be a #PF.
Indeed it is, let's move this discussion to that thread.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-09-20 17:43 UTC | newest]
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2018-09-18 23:03 [PATCH RESEND] kvm/x86: propagate fetch fault into guest Peng Hao
2018-09-19 14:33 ` Sean Christopherson
2018-09-20 16:32 ` Paolo Bonzini
2018-09-20 17:42 ` Sean Christopherson
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