From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/3] KVM: x86: Move #PF retry tracking variables into emulation context
Date: Wed, 19 Feb 2020 07:16:44 -0800 [thread overview]
Message-ID: <20200219151644.GB15888@linux.intel.com> (raw)
In-Reply-To: <40c8d560-1a5d-d592-5682-720980ca3dd9@redhat.com>
On Wed, Feb 19, 2020 at 09:13:00AM +0100, Paolo Bonzini wrote:
> On 19/02/20 00:03, Sean Christopherson wrote:
> > Move last_retry_eip and last_retry_addr into the emulation context as
> > they are specific to retrying an instruction after emulation failure.
> >
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
>
> I'm not sure about this, since it's not used by emulate.c. The other
> two patches are good.
The easy solution to that is to move retry_instruction() into emulate.c.
That would also allow making x86_page_table_writing_insn() static. All
other functions invoked from retry_instruction() are exposed via kvm_host.h.
Moving last_retry_* into the emulator context hopefully makes it more clear
that this code is the only user of the variables, e.g. last_retry_eip can't
be set by some other non-emulator flow.
if (ctxt->eip == last_retry_eip && last_retry_addr == cr2)
return false;
vcpu->arch.last_retry_eip = ctxt->eip;
vcpu->arch.last_retry_addr = cr2;
> > ---
> > arch/x86/include/asm/kvm_emulate.h | 4 ++++
> > arch/x86/include/asm/kvm_host.h | 3 ---
> > arch/x86/kvm/x86.c | 11 ++++++-----
> > 3 files changed, 10 insertions(+), 8 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
> > index a4ef19a6e612..a26c8de414e8 100644
> > --- a/arch/x86/include/asm/kvm_emulate.h
> > +++ b/arch/x86/include/asm/kvm_emulate.h
> > @@ -315,6 +315,10 @@ struct x86_emulate_ctxt {
> > bool gpa_available;
> > gpa_t gpa_val;
> >
> > + /* Track EIP and CR2/GPA when retrying faulting instruction on #PF. */
> > + unsigned long last_retry_eip;
> > + unsigned long last_retry_addr;
> > +
> > /*
> > * decode cache
> > */
> > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> > index 9c79c41eb5f6..6312ea32bb41 100644
> > --- a/arch/x86/include/asm/kvm_host.h
> > +++ b/arch/x86/include/asm/kvm_host.h
> > @@ -752,9 +752,6 @@ struct kvm_vcpu_arch {
> >
> > cpumask_var_t wbinvd_dirty_mask;
> >
> > - unsigned long last_retry_eip;
> > - unsigned long last_retry_addr;
> > -
> > struct {
> > bool halted;
> > gfn_t gfns[roundup_pow_of_two(ASYNC_PF_PER_VCPU)];
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index f88b72932c35..d19eb776f297 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -6407,6 +6407,7 @@ static void init_emulate_ctxt(struct kvm_vcpu *vcpu)
> >
> > kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l);
> >
> > + /* last_retry_{eip,addr} are persistent and must not be init'd here. */
> > ctxt->gpa_available = false;
> > ctxt->eflags = kvm_get_rflags(vcpu);
> > ctxt->tf = (ctxt->eflags & X86_EFLAGS_TF) != 0;
> > @@ -6557,8 +6558,8 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
> > struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
> > unsigned long last_retry_eip, last_retry_addr, gpa = cr2_or_gpa;
> >
> > - last_retry_eip = vcpu->arch.last_retry_eip;
> > - last_retry_addr = vcpu->arch.last_retry_addr;
> > + last_retry_eip = ctxt->last_retry_eip;
> > + last_retry_addr = ctxt->last_retry_addr;
> >
> > /*
> > * If the emulation is caused by #PF and it is non-page_table
> > @@ -6573,7 +6574,7 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
> > * and the address again, we can break out of the potential infinite
> > * loop.
> > */
> > - vcpu->arch.last_retry_eip = vcpu->arch.last_retry_addr = 0;
> > + ctxt->last_retry_eip = ctxt->last_retry_addr = 0;
> >
> > if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF))
> > return false;
> > @@ -6588,8 +6589,8 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
> > if (ctxt->eip == last_retry_eip && last_retry_addr == cr2_or_gpa)
> > return false;
> >
> > - vcpu->arch.last_retry_eip = ctxt->eip;
> > - vcpu->arch.last_retry_addr = cr2_or_gpa;
> > + ctxt->last_retry_eip = ctxt->eip;
> > + ctxt->last_retry_addr = cr2_or_gpa;
> >
> > if (!vcpu->arch.mmu->direct_map)
> > gpa = kvm_mmu_gva_to_gpa_write(vcpu, cr2_or_gpa, NULL);
> >
>
next prev parent reply other threads:[~2020-02-19 15:17 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-18 23:03 [PATCH v2 0/3] KVM: x86: Minor emulator cleanup Sean Christopherson
2020-02-18 23:03 ` [PATCH v2 1/3] KVM: x86: Add EMULTYPE_PF when emulation is triggered by a page fault Sean Christopherson
2020-02-19 9:01 ` Xiaoyao Li
2020-02-20 20:11 ` Sean Christopherson
2020-02-21 2:59 ` Xiaoyao Li
2020-02-21 17:12 ` Paolo Bonzini
2020-02-18 23:03 ` [PATCH v2 2/3] KVM: x86: Move gpa_val and gpa_available into the emulator context Sean Christopherson
2020-02-18 23:03 ` [PATCH v2 3/3] KVM: x86: Move #PF retry tracking variables into emulation context Sean Christopherson
2020-02-19 8:13 ` Paolo Bonzini
2020-02-19 15:16 ` Sean Christopherson [this message]
2020-02-21 17:14 ` Paolo Bonzini
2020-02-21 18:28 ` Sean Christopherson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200219151644.GB15888@linux.intel.com \
--to=sean.j.christopherson@intel.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).