On 13.05.25 18:34, Fuad Tabba wrote:
From: Ackerley Tng <ackerleytng@xxxxxxxxxx>
This patch adds kvm_gmem_max_mapping_level(), which always returns
PG_LEVEL_4K since guest_memfd only supports 4K pages for now.
When guest_memfd supports shared memory, max_mapping_level (especially
when recovering huge pages - see call to __kvm_mmu_max_mapping_level()
from recover_huge_pages_range()) should take input from
guest_memfd.
Input from guest_memfd should be taken in these cases:
+ if the memslot supports shared memory (guest_memfd is used for
shared memory, or in future both shared and private memory) or
+ if the memslot is only used for private memory and that gfn is
private.
If the memslot doesn't use guest_memfd, figure out the
max_mapping_level using the host page tables like before.
This patch also refactors and inlines the other call to
__kvm_mmu_max_mapping_level().
In kvm_mmu_hugepage_adjust(), guest_memfd's input is already
provided (if applicable) in fault->max_level. Hence, there is no need
to query guest_memfd.
lpage_info is queried like before, and then if the fault is not from
guest_memfd, adjust fault->req_level based on input from host page
tables.
Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
Signed-off-by: Fuad Tabba <tabba@xxxxxxxxxx>
---
arch/x86/kvm/mmu/mmu.c | 92 ++++++++++++++++++++++++++--------------
include/linux/kvm_host.h | 7 +++
virt/kvm/guest_memfd.c | 12 ++++++
3 files changed, 79 insertions(+), 32 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index cfbb471f7c70..9e0bc8114859 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3256,12 +3256,11 @@ static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn,
return level;
}
[...]
static u8 kvm_max_level_for_fault_and_order(struct kvm *kvm,
struct kvm_page_fault *fault,
int order)
@@ -4523,7 +4551,7 @@ static int __kvm_mmu_faultin_pfn(struct kvm_vcpu *vcpu,
{
unsigned int foll = fault->write ? FOLL_WRITE : 0;
- if (fault->is_private || kvm_gmem_memslot_supports_shared(fault->slot))
+ if (fault_from_gmem(fault))
Should this change rather have been done in the previous patch?
(then only adjust fault_from_gmem() in this function as required)
return kvm_mmu_faultin_pfn_gmem(vcpu, fault);
foll |= FOLL_NOWAIT;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index de7b46ee1762..f9bb025327c3 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -2560,6 +2560,7 @@ static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn)
int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
gfn_t gfn, kvm_pfn_t *pfn, struct page **page,
int *max_order);
+int kvm_gmem_mapping_order(const struct kvm_memory_slot *slot, gfn_t gfn);
#else
static inline int kvm_gmem_get_pfn(struct kvm *kvm,
struct kvm_memory_slot *slot, gfn_t gfn,
@@ -2569,6 +2570,12 @@ static inline int kvm_gmem_get_pfn(struct kvm *kvm,
KVM_BUG_ON(1, kvm);
return -EIO;
}
+static inline int kvm_gmem_mapping_order(const struct kvm_memory_slot *slot,
+ gfn_t gfn)
Probably should indent with two tabs here.
--
Cheers,
David / dhildenb
