Re: [PATCH 2/4] kvm: Merge "atomic" and "write" in __gfn_to_pfn_memslot()
From: John Hubbard
Date: Mon Jun 27 2022 - 22:17:21 EST
On 6/22/22 14:36, Peter Xu wrote:
Merge two boolean parameters into a bitmask flag called kvm_gtp_flag_t for
__gfn_to_pfn_memslot(). This cleans the parameter lists, and also prepare
for new boolean to be added to __gfn_to_pfn_memslot().
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
---
arch/arm64/kvm/mmu.c | 5 ++--
arch/powerpc/kvm/book3s_64_mmu_hv.c | 5 ++--
arch/powerpc/kvm/book3s_64_mmu_radix.c | 5 ++--
arch/x86/kvm/mmu/mmu.c | 10 +++----
include/linux/kvm_host.h | 9 ++++++-
virt/kvm/kvm_main.c | 37 +++++++++++++++-----------
virt/kvm/kvm_mm.h | 6 +++--
virt/kvm/pfncache.c | 2 +-
8 files changed, 49 insertions(+), 30 deletions(-)
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index f5651a05b6a8..ce1edb512b4e 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1204,8 +1204,9 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
*/
smp_rmb();
- pfn = __gfn_to_pfn_memslot(memslot, gfn, false, NULL,
- write_fault, &writable, NULL);
+ pfn = __gfn_to_pfn_memslot(memslot, gfn,
+ write_fault ? KVM_GTP_WRITE : 0,
+ NULL, &writable, NULL);
if (pfn == KVM_PFN_ERR_HWPOISON) {
kvm_send_hwpoison_signal(hva, vma_shift);
return 0;
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 514fd45c1994..e2769d58dd87 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -598,8 +598,9 @@ 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, NULL,
- writing, &write_ok, NULL);
+ pfn = __gfn_to_pfn_memslot(memslot, gfn,
+ writing ? KVM_GTP_WRITE : 0,
+ NULL, &write_ok, NULL);
if (is_error_noslot_pfn(pfn))
return -EFAULT;
page = NULL;
diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
index 42851c32ff3b..232b17c75b83 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
@@ -845,8 +845,9 @@ 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, NULL,
- writing, upgrade_p, NULL);
+ pfn = __gfn_to_pfn_memslot(memslot, gfn,
+ writing ? KVM_GTP_WRITE : 0,
+ NULL, upgrade_p, NULL);
if (is_error_noslot_pfn(pfn))
return -EFAULT;
page = NULL;
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index f4653688fa6d..e92f1ab63d6a 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3968,6 +3968,7 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work)
static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
{
+ kvm_gtp_flag_t flags = fault->write ? KVM_GTP_WRITE : 0;
struct kvm_memory_slot *slot = fault->slot;
bool async;
@@ -3999,8 +4000,8 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
}
async = false;
- fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, false, &async,
- fault->write, &fault->map_writable,
+ fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, flags,
+ &async, &fault->map_writable,
&fault->hva);
if (!async)
return RET_PF_CONTINUE; /* *pfn has correct page already */
@@ -4016,9 +4017,8 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
}
}
- fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, false, NULL,
- fault->write, &fault->map_writable,
- &fault->hva);
+ fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, flags, NULL,
+ &fault->map_writable, &fault->hva);
The flags arg does improve the situation, yes.
return RET_PF_CONTINUE;
}
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c20f2d55840c..b646b6fcaec6 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1146,8 +1146,15 @@ 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);
+
+/* gfn_to_pfn (gtp) flags */
+typedef unsigned int __bitwise kvm_gtp_flag_t;
A minor naming problem: GTP and especially gtp_flags is way too close
to gfp_flags. It will make people either wonder if it's a typo, or
worse, *assume* that it's a typo. :)
Yes, "read the code", but if you can come up with a better TLA than GTP
here, let's consider using it.
Overall, the change looks like an improvement, even though
write_fault ? KVM_GTP_WRITE : 0
is not wonderful. But improving *that* leads to a a big pile of diffs
that are rather beyond the scope here.
thanks,
--
John Hubbard
NVIDIA
+
+#define KVM_GTP_WRITE ((__force kvm_gtp_flag_t) BIT(0))
+#define KVM_GTP_ATOMIC ((__force kvm_gtp_flag_t) BIT(1))
+
kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn,
- bool atomic, bool *async, bool write_fault,
+ kvm_gtp_flag_t gtp_flags, bool *async,
bool *writable, hva_t *hva);
void kvm_release_pfn_clean(kvm_pfn_t pfn);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 64ec2222a196..952400b42ee9 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2444,9 +2444,11 @@ static bool hva_to_pfn_fast(unsigned long addr, bool write_fault,
* The slow path to get the pfn of the specified host virtual address,
* 1 indicates success, -errno is returned if error is detected.
*/
-static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,
+static int hva_to_pfn_slow(unsigned long addr, bool *async,
+ kvm_gtp_flag_t gtp_flags,
bool *writable, kvm_pfn_t *pfn)
{
+ bool write_fault = gtp_flags & KVM_GTP_WRITE;
unsigned int flags = FOLL_HWPOISON;
struct page *page;
int npages = 0;
@@ -2565,20 +2567,22 @@ 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 can sleep
+ * @gtp_flags: kvm_gtp_flag_t flags (atomic, write, ..)
* @async: whether this function need to wait IO complete if the
* host page is not in the memory
- * @write_fault: whether we should get a writable host page
* @writable: whether it allows to map a writable host page for !@write_fault
*
- * The function will map a writable host page for these two cases:
+ * The function will map a writable (KVM_GTP_WRITE set) host page for these
+ * two cases:
* 1): @write_fault = true
* 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 *async,
- bool write_fault, bool *writable)
+kvm_pfn_t hva_to_pfn(unsigned long addr, kvm_gtp_flag_t gtp_flags, bool *async,
+ bool *writable)
{
+ bool write_fault = gtp_flags & KVM_GTP_WRITE;
+ bool atomic = gtp_flags & KVM_GTP_ATOMIC;
struct vm_area_struct *vma;
kvm_pfn_t pfn = 0;
int npages, r;
@@ -2592,7 +2596,7 @@ kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,
if (atomic)
return KVM_PFN_ERR_FAULT;
- npages = hva_to_pfn_slow(addr, async, write_fault, writable, &pfn);
+ npages = hva_to_pfn_slow(addr, async, gtp_flags, writable, &pfn);
if (npages == 1)
return pfn;
@@ -2625,10 +2629,11 @@ kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,
}
kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn,
- bool atomic, bool *async, bool write_fault,
+ kvm_gtp_flag_t gtp_flags, bool *async,
bool *writable, hva_t *hva)
{
- unsigned long addr = __gfn_to_hva_many(slot, gfn, NULL, write_fault);
+ unsigned long addr = __gfn_to_hva_many(slot, gfn, NULL,
+ gtp_flags & KVM_GTP_WRITE);
if (hva)
*hva = addr;
@@ -2651,28 +2656,30 @@ kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn,
writable = NULL;
}
- return hva_to_pfn(addr, atomic, async, write_fault,
- writable);
+ return hva_to_pfn(addr, gtp_flags, async, 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, NULL,
- write_fault, writable, NULL);
+ return __gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn,
+ write_fault ? KVM_GTP_WRITE : 0,
+ NULL, 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, NULL, true, NULL, NULL);
+ return __gfn_to_pfn_memslot(slot, gfn, KVM_GTP_WRITE,
+ NULL, 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, NULL, true, NULL, NULL);
+ return __gfn_to_pfn_memslot(slot, gfn, KVM_GTP_WRITE | KVM_GTP_ATOMIC,
+ NULL, NULL, NULL);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn_memslot_atomic);
diff --git a/virt/kvm/kvm_mm.h b/virt/kvm/kvm_mm.h
index 41da467d99c9..1c870911eb48 100644
--- a/virt/kvm/kvm_mm.h
+++ b/virt/kvm/kvm_mm.h
@@ -3,6 +3,8 @@
#ifndef __KVM_MM_H__
#define __KVM_MM_H__ 1
+#include <linux/kvm_host.h>
+
/*
* Architectures can choose whether to use an rwlock or spinlock
* for the mmu_lock. These macros, for use in common code
@@ -24,8 +26,8 @@
#define KVM_MMU_READ_UNLOCK(kvm) spin_unlock(&(kvm)->mmu_lock)
#endif /* KVM_HAVE_MMU_RWLOCK */
-kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,
- bool write_fault, bool *writable);
+kvm_pfn_t hva_to_pfn(unsigned long addr, kvm_gtp_flag_t gtp_flags, bool *async,
+ 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 dd84676615f1..0f9f6b5d2fbb 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -123,7 +123,7 @@ static kvm_pfn_t hva_to_pfn_retry(struct kvm *kvm, unsigned long uhva)
smp_rmb();
/* We always request a writeable mapping */
- new_pfn = hva_to_pfn(uhva, false, NULL, true, NULL);
+ new_pfn = hva_to_pfn(uhva, KVM_GTP_WRITE, NULL, NULL);
if (is_error_noslot_pfn(new_pfn))
break;