[PATCH v13 12/85] KVM: Drop @atomic param from gfn=>pfn and hva=>pfn APIs

From: Sean Christopherson
Date: Thu Oct 10 2024 - 14:29:38 EST

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Drop @atomic from the myriad "to_pfn" APIs now that all callers pass
"false", and remove a comment blurb about KVM running only the "GUP fast"
part in atomic context.

No functional change intended.

Reviewed-by: Alex Bennée <alex.bennee@xxxxxxxxxx>
Tested-by: Alex Bennée <alex.bennee@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
Documentation/virt/kvm/locking.rst | 4 +--
arch/arm64/kvm/mmu.c | 2 +-
arch/powerpc/kvm/book3s_64_mmu_hv.c | 2 +-
arch/powerpc/kvm/book3s_64_mmu_radix.c | 2 +-
arch/x86/kvm/mmu/mmu.c | 12 ++++----
include/linux/kvm_host.h | 4 +--
virt/kvm/kvm_main.c | 39 ++++++--------------------
virt/kvm/kvm_mm.h | 4 +--
virt/kvm/pfncache.c | 2 +-
9 files changed, 23 insertions(+), 48 deletions(-)

diff --git a/Documentation/virt/kvm/locking.rst b/Documentation/virt/kvm/locking.rst
index 3d8bf40ca448..f463ac42ac7a 100644
--- a/Documentation/virt/kvm/locking.rst
+++ b/Documentation/virt/kvm/locking.rst
@@ -135,8 +135,8 @@ We dirty-log for gfn1, that means gfn2 is lost in dirty-bitmap.
For direct sp, we can easily avoid it since the spte of direct sp is fixed
to gfn. For indirect sp, we disabled fast page fault for simplicity.

-A solution for indirect sp could be to pin the gfn, for example via
-kvm_vcpu_gfn_to_pfn_atomic, before the cmpxchg. After the pinning:
+A solution for indirect sp could be to pin the gfn before the cmpxchg. After
+the pinning:

- We have held the refcount of pfn; that means the pfn can not be freed and
be reused for another gfn.
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index a509b63bd4dd..a6e62cc9015c 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1569,7 +1569,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
mmu_seq = vcpu->kvm->mmu_invalidate_seq;
mmap_read_unlock(current->mm);

- pfn = __gfn_to_pfn_memslot(memslot, gfn, false, false, NULL,
+ pfn = __gfn_to_pfn_memslot(memslot, gfn, false, NULL,
write_fault, &writable, NULL);
if (pfn == KVM_PFN_ERR_HWPOISON) {
kvm_send_hwpoison_signal(hva, vma_shift);
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 1b51b1c4713b..8cd02ca4b1b8 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -613,7 +613,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_vcpu *vcpu,
write_ok = true;
} else {
/* Call KVM generic code to do the slow-path check */
- pfn = __gfn_to_pfn_memslot(memslot, gfn, false, false, NULL,
+ pfn = __gfn_to_pfn_memslot(memslot, gfn, false, NULL,
writing, &write_ok, NULL);
if (is_error_noslot_pfn(pfn))
return -EFAULT;
diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
index 408d98f8a514..26a969e935e3 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
@@ -852,7 +852,7 @@ int kvmppc_book3s_instantiate_page(struct kvm_vcpu *vcpu,
unsigned long pfn;

/* Call KVM generic code to do the slow-path check */
- pfn = __gfn_to_pfn_memslot(memslot, gfn, false, false, NULL,
+ pfn = __gfn_to_pfn_memslot(memslot, gfn, false, NULL,
writing, upgrade_p, NULL);
if (is_error_noslot_pfn(pfn))
return -EFAULT;
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 5fe45ab0e818..0e235f276ee5 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4380,9 +4380,9 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
return kvm_faultin_pfn_private(vcpu, fault);

async = false;
- fault->pfn = __gfn_to_pfn_memslot(fault->slot, fault->gfn, false, false,
- &async, fault->write,
- &fault->map_writable, &fault->hva);
+ fault->pfn = __gfn_to_pfn_memslot(fault->slot, fault->gfn, false, &async,
+ fault->write, &fault->map_writable,
+ &fault->hva);
if (!async)
return RET_PF_CONTINUE; /* *pfn has correct page already */

@@ -4402,9 +4402,9 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
* to wait for IO. Note, gup always bails if it is unable to quickly
* get a page and a fatal signal, i.e. SIGKILL, is pending.
*/
- fault->pfn = __gfn_to_pfn_memslot(fault->slot, fault->gfn, false, true,
- NULL, fault->write,
- &fault->map_writable, &fault->hva);
+ fault->pfn = __gfn_to_pfn_memslot(fault->slot, fault->gfn, true, NULL,
+ fault->write, &fault->map_writable,
+ &fault->hva);
return RET_PF_CONTINUE;
}

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 56e7cde8c8b8..2faafc7a56ae 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1232,9 +1232,8 @@ kvm_pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn);
kvm_pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,
bool *writable);
kvm_pfn_t gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn);
-kvm_pfn_t gfn_to_pfn_memslot_atomic(const struct kvm_memory_slot *slot, gfn_t gfn);
kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn,
- bool atomic, bool interruptible, bool *async,
+ bool interruptible, bool *async,
bool write_fault, bool *writable, hva_t *hva);

void kvm_release_pfn_clean(kvm_pfn_t pfn);
@@ -1315,7 +1314,6 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn);

struct kvm_memslots *kvm_vcpu_memslots(struct kvm_vcpu *vcpu);
struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn);
-kvm_pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn);
kvm_pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn);
int kvm_vcpu_map(struct kvm_vcpu *vcpu, gpa_t gpa, struct kvm_host_map *map);
void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 957b4a6c9254..0bc077213d3e 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2756,8 +2756,7 @@ static inline int check_user_page_hwpoison(unsigned long addr)

/*
* The fast path to get the writable pfn which will be stored in @pfn,
- * true indicates success, otherwise false is returned. It's also the
- * only part that runs if we can in atomic context.
+ * true indicates success, otherwise false is returned.
*/
static bool hva_to_pfn_fast(unsigned long addr, bool write_fault,
bool *writable, kvm_pfn_t *pfn)
@@ -2922,7 +2921,6 @@ static int hva_to_pfn_remapped(struct vm_area_struct *vma,
/*
* Pin guest page in memory and return its pfn.
* @addr: host virtual address which maps memory to the guest
- * @atomic: whether this function is forbidden from sleeping
* @interruptible: whether the process can be interrupted by non-fatal signals
* @async: whether this function need to wait IO complete if the
* host page is not in the memory
@@ -2934,22 +2932,16 @@ static int hva_to_pfn_remapped(struct vm_area_struct *vma,
* 2): @write_fault = false && @writable, @writable will tell the caller
* whether the mapping is writable.
*/
-kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool interruptible,
- bool *async, bool write_fault, bool *writable)
+kvm_pfn_t hva_to_pfn(unsigned long addr, bool interruptible, bool *async,
+ bool write_fault, bool *writable)
{
struct vm_area_struct *vma;
kvm_pfn_t pfn;
int npages, r;

- /* we can do it either atomically or asynchronously, not both */
- BUG_ON(atomic && async);
-
if (hva_to_pfn_fast(addr, write_fault, writable, &pfn))
return pfn;

- if (atomic)
- return KVM_PFN_ERR_FAULT;
-
npages = hva_to_pfn_slow(addr, async, write_fault, interruptible,
writable, &pfn);
if (npages == 1)
@@ -2986,7 +2978,7 @@ kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool interruptible,
}

kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn,
- bool atomic, bool interruptible, bool *async,
+ bool interruptible, bool *async,
bool write_fault, bool *writable, hva_t *hva)
{
unsigned long addr = __gfn_to_hva_many(slot, gfn, NULL, write_fault);
@@ -3008,39 +3000,24 @@ kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn,
writable = NULL;
}

- return hva_to_pfn(addr, atomic, interruptible, async, write_fault,
- writable);
+ return hva_to_pfn(addr, interruptible, async, write_fault, writable);
}
EXPORT_SYMBOL_GPL(__gfn_to_pfn_memslot);

kvm_pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,
bool *writable)
{
- return __gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn, false, false,
- NULL, write_fault, writable, NULL);
+ return __gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn, false, NULL,
+ write_fault, writable, NULL);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn_prot);

kvm_pfn_t gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn)
{
- return __gfn_to_pfn_memslot(slot, gfn, false, false, NULL, true,
- NULL, NULL);
+ return __gfn_to_pfn_memslot(slot, gfn, false, NULL, true, NULL, NULL);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn_memslot);

-kvm_pfn_t gfn_to_pfn_memslot_atomic(const struct kvm_memory_slot *slot, gfn_t gfn)
-{
- return __gfn_to_pfn_memslot(slot, gfn, true, false, NULL, true,
- NULL, NULL);
-}
-EXPORT_SYMBOL_GPL(gfn_to_pfn_memslot_atomic);
-
-kvm_pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn)
-{
- return gfn_to_pfn_memslot_atomic(kvm_vcpu_gfn_to_memslot(vcpu, gfn), gfn);
-}
-EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_pfn_atomic);
-
kvm_pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
{
return gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn);
diff --git a/virt/kvm/kvm_mm.h b/virt/kvm/kvm_mm.h
index 715f19669d01..a3fa86f60d6c 100644
--- a/virt/kvm/kvm_mm.h
+++ b/virt/kvm/kvm_mm.h
@@ -20,8 +20,8 @@
#define KVM_MMU_UNLOCK(kvm) spin_unlock(&(kvm)->mmu_lock)
#endif /* KVM_HAVE_MMU_RWLOCK */

-kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool interruptible,
- bool *async, bool write_fault, bool *writable);
+kvm_pfn_t hva_to_pfn(unsigned long addr, bool interruptible, bool *async,
+ bool write_fault, bool *writable);

#ifdef CONFIG_HAVE_KVM_PFNCACHE
void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm,
diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index f0039efb9e1e..58c706a610e5 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -198,7 +198,7 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc)
}

/* We always request a writeable mapping */
- new_pfn = hva_to_pfn(gpc->uhva, false, false, NULL, true, NULL);
+ new_pfn = hva_to_pfn(gpc->uhva, false, NULL, true, NULL);
if (is_error_noslot_pfn(new_pfn))
goto out_error;

--
2.47.0.rc1.288.g06298d1525-goog

Next message: Sean Christopherson: "[PATCH v13 13/85] KVM: Annotate that all paths in hva_to_pfn() might sleep"
Previous message: Fan Ni: "Re: [PATCH v4 19/28] cxl/mem: Configure dynamic capacity interrupts"
In reply to: Sean Christopherson: "[PATCH v13 11/85] KVM: Rename gfn_to_page_many_atomic() to kvm_prefetch_pages()"
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