From: Sean Christopherson <seanjc@google.com>
To: Isaku Yamahata <isaku.yamahata@intel.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
isaku.yamahata@gmail.com
Subject: Re: [RFC PATCH 00/10] KVM: x86/mmu: simplify argument to kvm page fault handler
Date: Wed, 26 May 2021 21:10:47 +0000 [thread overview]
Message-ID: <YK65V++S2Kt1OLTu@google.com> (raw)
In-Reply-To: <cover.1618914692.git.isaku.yamahata@intel.com>
On Tue, Apr 20, 2021, Isaku Yamahata wrote:
> This is a preliminary clean up for TDX which complicates KVM page fault
> execution path.
Ooh, a series to complicate the page fault path! ;-)
Grammatical snarkiness aside, I'm all in favor of adding a struct to collect the
page fault collateral. Overarching feedback:
- Have kvm_mmu_do_page_fault() handle initialization of the struct. That
will allow making most of the fields const, and will avoid the rather painful
kvm_page_fault_init().
- Pass @vcpu separately. Yes, it's associated with the fault, but literally
the first line in every consumer is "struct kvm_vcpu *vcpu = kpf->vcpu;".
- Use "fault" instead of "kpf", mostly because it reads better for people that
aren't intimately familiar with the code, but also to avoid having to refactor
a huge amount of code if we decide to rename kvm_page_fault, e.g. if we decide
to use that name to return fault information to userspace.
- Snapshot anything that is computed in multiple places, even if it is
derivative of existing info. E.g. it probably makes sense to grab
write/fetch (or exec).
E.g. I'm thinking something like
struct kvm_page_fault {
const gpa_t cr2_or_gpa;
const u32 error_code;
const bool write;
const bool read;
const bool fetch;
const bool prefault;
const bool is_tdp;
gfn_t gfn;
hva_t hva;
int max_level;
kvm_pfn_t pfn;
bool map_writable;
};
int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault);
static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
u32 err, bool prefault)
{
struct kvm_page_fault fault = {
.cr2_or_gpa = cr2_or_gpa,
.error_code = err,
.write = err & PFERR_WRITE_MASK,
.fetch = err & PFERR_FETCH_MASK,
.perm = ...
.rsvd = err & PFERR_RSVD_MASK,
.is_tdp = vcpu->arch.mmu->page_fault == kvm_tdp_page_fault,
...
};
#ifdef CONFIG_RETPOLINE
if (likely(fault.is_tdp))
return kvm_tdp_page_fault(vcpu, &fault);
#endif
return vcpu->arch.mmu->page_fault(vcpu, &fault);
}
next prev parent reply other threads:[~2021-05-26 21:11 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-20 10:39 [RFC PATCH 00/10] KVM: x86/mmu: simplify argument to kvm page fault handler Isaku Yamahata
2021-04-20 10:39 ` [RFC PATCH 01/10] KVM: x86/mmu: make kvm_mmu_do_page_fault() receive single argument Isaku Yamahata
2021-04-20 10:39 ` [RFC PATCH 02/10] KVM: x86/mmu: make kvm_mmu:page_fault " Isaku Yamahata
2021-04-20 10:39 ` [RFC PATCH 03/10] KVM: x86/mmu: make direct_page_fault() " Isaku Yamahata
2021-04-20 10:39 ` [RFC PATCH 04/10] KVM: x86/mmu: make try_async_pf() " Isaku Yamahata
2021-04-20 10:39 ` [RFC PATCH 05/10] KVM: x86/mmu: make page_fault_handle_page_track() " Isaku Yamahata
2021-04-20 10:39 ` [RFC PATCH 06/10] KVM: x86/mmu: make handle_abnormal_pfn() " Isaku Yamahata
2021-04-20 10:39 ` [RFC PATCH 07/10] KVM: x86/mmu: make fast_page_fault() " Isaku Yamahata
2021-04-20 10:39 ` [RFC PATCH 08/10] KVM: x86/mmu: make __direct_map() " Isaku Yamahata
2021-04-20 10:39 ` [RFC PATCH 09/10] KVM: x86/mmu: make kvm_tdp_mmu_map() " Isaku Yamahata
2021-04-20 10:39 ` [RFC PATCH 10/10] KVM: x86/mmu: make FNAME(fetch) " Isaku Yamahata
2021-05-26 21:10 ` Sean Christopherson [this message]
2021-06-10 12:45 ` [RFC PATCH 00/10] KVM: x86/mmu: simplify argument to kvm page fault handler Paolo Bonzini
2021-06-10 22:00 ` Isaku Yamahata
2021-07-29 16:48 ` David Matlack
2021-07-29 17:17 ` Paolo Bonzini
2021-07-29 17:24 ` David Matlack
2021-08-06 16:07 ` Paolo Bonzini
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