[PATCH v12 45/84] KVM: guest_memfd: Provide "struct page" as output from kvm_gmem_get_pfn()
From: Sean Christopherson
Date: Fri Jul 26 2024 - 20:09:00 EST
Provide the "struct page" associated with a guest_memfd pfn as an output
from __kvm_gmem_get_pfn() so that KVM guest page fault handlers can
directly put the page instead of having to rely on
kvm_pfn_to_refcounted_page().
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/mmu/mmu.c | 2 +-
arch/x86/kvm/svm/sev.c | 10 ++++++----
include/linux/kvm_host.h | 6 ++++--
virt/kvm/guest_memfd.c | 19 +++++++++++--------
4 files changed, 22 insertions(+), 15 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 53555ea5e5bb..146e57c9c86d 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4353,7 +4353,7 @@ static int kvm_mmu_faultin_pfn_private(struct kvm_vcpu *vcpu,
}
r = kvm_gmem_get_pfn(vcpu->kvm, fault->slot, fault->gfn, &fault->pfn,
- &max_order);
+ &fault->refcounted_page, &max_order);
if (r) {
kvm_mmu_prepare_memory_fault_exit(vcpu, fault);
return r;
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 62f63fd714df..5c125e4c1096 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3847,6 +3847,7 @@ static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu)
if (VALID_PAGE(svm->sev_es.snp_vmsa_gpa)) {
gfn_t gfn = gpa_to_gfn(svm->sev_es.snp_vmsa_gpa);
struct kvm_memory_slot *slot;
+ struct page *page;
kvm_pfn_t pfn;
slot = gfn_to_memslot(vcpu->kvm, gfn);
@@ -3857,7 +3858,7 @@ static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu)
* The new VMSA will be private memory guest memory, so
* retrieve the PFN from the gmem backend.
*/
- if (kvm_gmem_get_pfn(vcpu->kvm, slot, gfn, &pfn, NULL))
+ if (kvm_gmem_get_pfn(vcpu->kvm, slot, gfn, &pfn, &page, NULL))
return -EINVAL;
/*
@@ -3886,7 +3887,7 @@ static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu)
* changes then care should be taken to ensure
* svm->sev_es.vmsa is pinned through some other means.
*/
- kvm_release_pfn_clean(pfn);
+ kvm_release_page_clean(page);
}
/*
@@ -4686,6 +4687,7 @@ void sev_handle_rmp_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code)
struct kvm_memory_slot *slot;
struct kvm *kvm = vcpu->kvm;
int order, rmp_level, ret;
+ struct page *page;
bool assigned;
kvm_pfn_t pfn;
gfn_t gfn;
@@ -4712,7 +4714,7 @@ void sev_handle_rmp_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code)
return;
}
- ret = kvm_gmem_get_pfn(kvm, slot, gfn, &pfn, &order);
+ ret = kvm_gmem_get_pfn(kvm, slot, gfn, &pfn, &page, &order);
if (ret) {
pr_warn_ratelimited("SEV: Unexpected RMP fault, no backing page for private GPA 0x%llx\n",
gpa);
@@ -4770,7 +4772,7 @@ void sev_handle_rmp_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code)
out:
trace_kvm_rmp_fault(vcpu, gpa, pfn, error_code, rmp_level, ret);
out_no_trace:
- put_page(pfn_to_page(pfn));
+ kvm_release_page_unused(page);
}
static bool is_pfn_range_shared(kvm_pfn_t start, kvm_pfn_t end)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index e0548ae92659..9d2a97eb30e4 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -2462,11 +2462,13 @@ static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn)
#ifdef CONFIG_KVM_PRIVATE_MEM
int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
- gfn_t gfn, kvm_pfn_t *pfn, int *max_order);
+ gfn_t gfn, kvm_pfn_t *pfn, struct page **page,
+ int *max_order);
#else
static inline int kvm_gmem_get_pfn(struct kvm *kvm,
struct kvm_memory_slot *slot, gfn_t gfn,
- kvm_pfn_t *pfn, int *max_order)
+ kvm_pfn_t *pfn, struct page **page,
+ int *max_order)
{
KVM_BUG_ON(1, kvm);
return -EIO;
diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index 1c509c351261..ad1f9e73cd13 100644
--- a/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c
@@ -542,12 +542,12 @@ void kvm_gmem_unbind(struct kvm_memory_slot *slot)
}
static int __kvm_gmem_get_pfn(struct file *file, struct kvm_memory_slot *slot,
- gfn_t gfn, kvm_pfn_t *pfn, int *max_order, bool prepare)
+ gfn_t gfn, kvm_pfn_t *pfn, struct page **page,
+ int *max_order, bool prepare)
{
pgoff_t index = gfn - slot->base_gfn + slot->gmem.pgoff;
struct kvm_gmem *gmem = file->private_data;
struct folio *folio;
- struct page *page;
int r;
if (file != slot->gmem.file) {
@@ -571,9 +571,9 @@ static int __kvm_gmem_get_pfn(struct file *file, struct kvm_memory_slot *slot,
return -EHWPOISON;
}
- page = folio_file_page(folio, index);
+ *page = folio_file_page(folio, index);
- *pfn = page_to_pfn(page);
+ *pfn = page_to_pfn(*page);
if (max_order)
*max_order = 0;
@@ -585,7 +585,8 @@ static int __kvm_gmem_get_pfn(struct file *file, struct kvm_memory_slot *slot,
}
int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
- gfn_t gfn, kvm_pfn_t *pfn, int *max_order)
+ gfn_t gfn, kvm_pfn_t *pfn, struct page **page,
+ int *max_order)
{
struct file *file = kvm_gmem_get_file(slot);
int r;
@@ -593,7 +594,7 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
if (!file)
return -EFAULT;
- r = __kvm_gmem_get_pfn(file, slot, gfn, pfn, max_order, true);
+ r = __kvm_gmem_get_pfn(file, slot, gfn, pfn, page, max_order, true);
fput(file);
return r;
}
@@ -604,6 +605,7 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, long
{
struct file *file;
struct kvm_memory_slot *slot;
+ struct page *page;
void __user *p;
int ret = 0, max_order;
@@ -633,7 +635,8 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, long
break;
}
- ret = __kvm_gmem_get_pfn(file, slot, gfn, &pfn, &max_order, false);
+ ret = __kvm_gmem_get_pfn(file, slot, gfn, &pfn, &page,
+ &max_order, false);
if (ret)
break;
@@ -644,7 +647,7 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, long
p = src ? src + i * PAGE_SIZE : NULL;
ret = post_populate(kvm, gfn, pfn, p, max_order, opaque);
- put_page(pfn_to_page(pfn));
+ put_page(page);
if (ret)
break;
}
--
2.46.0.rc1.232.g9752f9e123-goog