diff mbox series

[v6,01/16] KVM: TDP_MMU: Go to next level if smaller private mapping exists

Message ID 439c7be59c35a03bced88a44567431e721fab3da.1699368363.git.isaku.yamahata@intel.com (mailing list archive)
State New, archived
Headers show
Series KVM TDX: TDP MMU: large page support | expand

Commit Message

Isaku Yamahata Nov. 7, 2023, 3 p.m. UTC
From: Xiaoyao Li <xiaoyao.li@intel.com>

Cannot map a private page as large page if any smaller mapping exists.

It has to wait for all the not-mapped smaller page to be mapped and
promote it to larger mapping.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Binbin Wu Nov. 16, 2023, 1:32 a.m. UTC | #1
On 11/7/2023 11:00 PM, isaku.yamahata@intel.com wrote:
> From: Xiaoyao Li <xiaoyao.li@intel.com>
>
> Cannot map a private page as large page if any smaller mapping exists.
>
> It has to wait for all the not-mapped smaller page to be mapped and
> promote it to larger mapping.
>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> ---
>   arch/x86/kvm/mmu/tdp_mmu.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
> index 2c5257628881..d806574f7f2d 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.c
> +++ b/arch/x86/kvm/mmu/tdp_mmu.c
> @@ -1287,7 +1287,8 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
>   	tdp_mmu_for_each_pte(iter, mmu, is_private, raw_gfn, raw_gfn + 1) {
>   		int r;
>   
> -		if (fault->nx_huge_page_workaround_enabled)
> +		if (fault->nx_huge_page_workaround_enabled ||
> +		    kvm_gfn_shared_mask(vcpu->kvm))
As I mentioned in 
https://lore.kernel.org/kvm/fef75d54-e319-5170-5f76-f5abc4856315@linux.intel.com/,
The change of this patch will not take effect.
If "fault->nx_huge_page_workaround_enabled" is false, the condition
"spte_to_child_sp(spte)->nx_huge_page_disallowed" will not be true.

IIUC, the function disallowed_hugepage_adjust() currently is only to handle
nx_huge_page_workaround, it seems no special handling needed for TD.
>   			disallowed_hugepage_adjust(fault, iter.old_spte, iter.level);
>   
>   		/*
Isaku Yamahata Nov. 17, 2023, 1:05 a.m. UTC | #2
On Thu, Nov 16, 2023 at 09:32:22AM +0800,
Binbin Wu <binbin.wu@linux.intel.com> wrote:

> 
> 
> On 11/7/2023 11:00 PM, isaku.yamahata@intel.com wrote:
> > From: Xiaoyao Li <xiaoyao.li@intel.com>
> > 
> > Cannot map a private page as large page if any smaller mapping exists.
> > 
> > It has to wait for all the not-mapped smaller page to be mapped and
> > promote it to larger mapping.
> > 
> > Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> > ---
> >   arch/x86/kvm/mmu/tdp_mmu.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
> > index 2c5257628881..d806574f7f2d 100644
> > --- a/arch/x86/kvm/mmu/tdp_mmu.c
> > +++ b/arch/x86/kvm/mmu/tdp_mmu.c
> > @@ -1287,7 +1287,8 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
> >   	tdp_mmu_for_each_pte(iter, mmu, is_private, raw_gfn, raw_gfn + 1) {
> >   		int r;
> > -		if (fault->nx_huge_page_workaround_enabled)
> > +		if (fault->nx_huge_page_workaround_enabled ||
> > +		    kvm_gfn_shared_mask(vcpu->kvm))
> As I mentioned in https://lore.kernel.org/kvm/fef75d54-e319-5170-5f76-f5abc4856315@linux.intel.com/,
> The change of this patch will not take effect.
> If "fault->nx_huge_page_workaround_enabled" is false, the condition
> "spte_to_child_sp(spte)->nx_huge_page_disallowed" will not be true.
> 
> IIUC, the function disallowed_hugepage_adjust() currently is only to handle
> nx_huge_page_workaround, it seems no special handling needed for TD.
> >   			disallowed_hugepage_adjust(fault, iter.old_spte, iter.level);
> >   		/*

You're correct. Now guest memfd memory attributes takes care of large page
mapping, this patch is uncessary.  Will drop this patch.
diff mbox series

Patch

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 2c5257628881..d806574f7f2d 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1287,7 +1287,8 @@  int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 	tdp_mmu_for_each_pte(iter, mmu, is_private, raw_gfn, raw_gfn + 1) {
 		int r;
 
-		if (fault->nx_huge_page_workaround_enabled)
+		if (fault->nx_huge_page_workaround_enabled ||
+		    kvm_gfn_shared_mask(vcpu->kvm))
 			disallowed_hugepage_adjust(fault, iter.old_spte, iter.level);
 
 		/*