From: Barret Rhoden <brho@google.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>,
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 1/3] KVM: x86/mmu: Tweak PSE hugepage handling to avoid 2M vs 4M conundrum
Date: Tue, 28 Apr 2020 10:07:27 -0400 [thread overview]
Message-ID: <3e60b34b-e160-2052-3066-c29867ccef64@google.com> (raw)
In-Reply-To: <20200428005422.4235-2-sean.j.christopherson@intel.com>
On 4/27/20 8:54 PM, Sean Christopherson wrote:
> Change the PSE hugepage handling in walk_addr_generic() to fire on any
> page level greater than PT_PAGE_TABLE_LEVEL, a.k.a. PG_LEVEL_4K. PSE
> paging only has two levels, so "== 2" and "> 1" are functionally the
> seam, i.e. this is a nop.
^ s/seam/same/
Barret
>
> A future patch will drop KVM's PT_*_LEVEL enums in favor of the kernel's
> PG_LEVEL_* enums, at which point "walker->level == PG_LEVEL_2M" is
> semantically incorrect (though still functionally ok).
>
> No functional change intended.
>
> Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> arch/x86/kvm/mmu/paging_tmpl.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
> index efec7d27b8c5..ca39bd315f70 100644
> --- a/arch/x86/kvm/mmu/paging_tmpl.h
> +++ b/arch/x86/kvm/mmu/paging_tmpl.h
> @@ -436,7 +436,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
> gfn = gpte_to_gfn_lvl(pte, walker->level);
> gfn += (addr & PT_LVL_OFFSET_MASK(walker->level)) >> PAGE_SHIFT;
>
> - if (PTTYPE == 32 && walker->level == PT_DIRECTORY_LEVEL && is_cpuid_PSE36())
> + if (PTTYPE == 32 && walker->level > PT_PAGE_TABLE_LEVEL && is_cpuid_PSE36())
> gfn += pse36_gfn_delta(pte);
>
> real_gpa = mmu->translate_gpa(vcpu, gfn_to_gpa(gfn), access, &walker->fault);
>
next prev parent reply other threads:[~2020-04-28 14:07 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-28 0:54 [PATCH 0/3] KVM: x86/mmu: Use kernel's PG_LEVEL_* enums Sean Christopherson
2020-04-28 0:54 ` [PATCH 1/3] KVM: x86/mmu: Tweak PSE hugepage handling to avoid 2M vs 4M conundrum Sean Christopherson
2020-04-28 14:07 ` Barret Rhoden [this message]
2020-04-28 0:54 ` [PATCH 2/3] KVM: x86/mmu: Move max hugepage level to a separate #define Sean Christopherson
2020-04-28 0:54 ` [PATCH 3/3] KVM: x86/mmu: Drop KVM's hugepage enums in favor of the kernel's enums Sean Christopherson
2020-04-28 14:14 ` [PATCH 0/3] KVM: x86/mmu: Use kernel's PG_LEVEL_* enums Barret Rhoden
2020-05-04 16:49 ` Paolo Bonzini
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