[v2,04/10] KVM: x86/mmu: Make __kvm_mmu_do_page_fault() return mapped level

Commit Message

Isaku Yamahata April 10, 2024, 10:07 p.m. UTC

From: Isaku Yamahata <[e-mail]>

The guest memory population logic will need to know what page size or level
(4K, 2M, ...) is mapped.

Signed-off-by: Isaku Yamahata <[e-mail]>
---
v2:
- Newly added.
---
 arch/x86/kvm/mmu/mmu_internal.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

Comments

Edgecombe, Rick P April 16, 2024, 2:40 p.m. UTC | #1

On Wed, 2024-04-10 at 15:07 -0700, [e-mail] wrote:
> From: Isaku Yamahata <[e-mail]>
> 
> The guest memory population logic will need to know what page size or level
> (4K, 2M, ...) is mapped.

TDX needs this, but do the normal VM users need to have it fixed to 4k? Is it
actually good?

> 
> Signed-off-by: Isaku Yamahata <[e-mail]>

Isaku Yamahata April 16, 2024, 11:59 p.m. UTC | #2

On Tue, Apr 16, 2024 at 02:40:39PM +0000,
"Edgecombe, Rick P" <[e-mail]> wrote:

> On Wed, 2024-04-10 at 15:07 -0700, [e-mail] wrote:
> > From: Isaku Yamahata <[e-mail]>
> > 
> > The guest memory population logic will need to know what page size or level
> > (4K, 2M, ...) is mapped.
> 
> TDX needs this, but do the normal VM users need to have it fixed to 4k? Is it
> actually good?

I meant that the function, kvm_arch_vcpu_map_memory(), in
[PATCH v2 06/10] KVM: x86: Implement kvm_arch_vcpu_map_memory() needs level.

No logic in this patch series enforces to fixed 4K. 
gmem_max_level() hook will determine it.

https://lore.kernel.org/all/[e-mail]/

I'll update the commit message to reflect it.

Patch

diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index 9baae6c223ee..b0a10f5a40dd 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -288,7 +288,8 @@  static inline void kvm_mmu_prepare_memory_fault_exit(struct kvm_vcpu *vcpu,
 }
 
 static inline int __kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
-					  u64 err, bool prefetch, int *emulation_type)
+					  u64 err, bool prefetch,
+					  int *emulation_type, u8 *level)
 {
 	struct kvm_page_fault fault = {
 		.addr = cr2_or_gpa,
@@ -330,6 +331,8 @@  static inline int __kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gp
 
 	if (fault.write_fault_to_shadow_pgtable && emulation_type)
 		*emulation_type |= EMULTYPE_WRITE_PF_TO_SP;
+	if (level)
+		*level = fault.goal_level;
 
 	return r;
 }
@@ -347,7 +350,8 @@  static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 	if (!prefetch)
 		vcpu->stat.pf_taken++;
 
-	r = __kvm_mmu_do_page_fault(vcpu, cr2_or_gpa, err, prefetch, emulation_type);
+	r = __kvm_mmu_do_page_fault(vcpu, cr2_or_gpa, err, prefetch,
+				    emulation_type, NULL);
 
 	/*
 	 * Similar to above, prefetch faults aren't truly spurious, and the