lkml.org 
[lkml]   [2018]   [Sep]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH RESEND] kvm/x86: propagate fetch fault into guest
From
Date
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);

\
 
 \ /
  Last update: 2018-09-19 16:34    [W:0.057 / U:2.052 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site