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Message-ID: <20240910163038.1298452-8-roypat@amazon.co.uk>
Date: Tue, 10 Sep 2024 17:30:33 +0100
From: Patrick Roy <roypat@...zon.co.uk>
To: <seanjc@...gle.com>, <pbonzini@...hat.com>, <tglx@...utronix.de>,
<mingo@...hat.com>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>,
<x86@...nel.org>, <hpa@...or.com>, <rostedt@...dmis.org>,
<mhiramat@...nel.org>, <mathieu.desnoyers@...icios.com>,
<kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-trace-kernel@...r.kernel.org>, <quic_eberman@...cinc.com>,
<dwmw@...zon.com>, <david@...hat.com>, <tabba@...gle.com>, <rppt@...nel.org>,
<linux-mm@...ck.org>, <dmatlack@...gle.com>
CC: Patrick Roy <roypat@...zon.co.uk>, <graf@...zon.com>,
<jgowans@...zon.com>, <derekmn@...zon.com>, <kalyazin@...zon.com>,
<xmarcalx@...zon.com>
Subject: [RFC PATCH v2 07/10] kvm: pfncache: invalidate when memory attributes change
Invalidate gfn_to_pfn_caches when the memory attributes of the gfn it
contains change.
Since gfn_to_pfn_caches are not hooked up to KVM's MMU notifiers, but
rather have to be invalidated right _before_ KVM's MMU notifiers are
triggers, adopt the approach used by
kvm_mmu_notifier_invalidate_range_start for invalidating gpcs inside
kvm_vm_set_mem_attributes.
Signed-off-by: Patrick Roy <roypat@...zon.co.uk>
---
include/linux/kvm_host.h | 1 +
virt/kvm/kvm_main.c | 5 +++++
virt/kvm/kvm_mm.h | 10 +++++++++
virt/kvm/pfncache.c | 45 ++++++++++++++++++++++++++++++++++++++++
4 files changed, 61 insertions(+)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index cd28eb34aaeb1..7d36164a2cee5 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -840,6 +840,7 @@ struct kvm {
#ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES
/* Protected by slots_locks (for writes) and RCU (for reads) */
struct xarray mem_attr_array;
+ bool attribute_change_in_progress;
#endif
char stats_id[KVM_STATS_NAME_SIZE];
};
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 13347fb03d4a9..183f7ce57a428 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2533,6 +2533,7 @@ static int kvm_vm_set_mem_attributes(struct kvm *kvm, gfn_t start, gfn_t end,
mutex_lock(&kvm->slots_lock);
+
/* Nothing to do if the entire range as the desired attributes. */
if (kvm_range_has_memory_attributes(kvm, start, end, attributes))
goto out_unlock;
@@ -2547,6 +2548,9 @@ static int kvm_vm_set_mem_attributes(struct kvm *kvm, gfn_t start, gfn_t end,
goto out_unlock;
}
+ kvm->attribute_change_in_progress = true;
+ gfn_to_pfn_cache_invalidate_gfns_start(kvm, start, end);
+
kvm_handle_gfn_range(kvm, &pre_set_range);
for (i = start; i < end; i++) {
@@ -2558,6 +2562,7 @@ static int kvm_vm_set_mem_attributes(struct kvm *kvm, gfn_t start, gfn_t end,
kvm_handle_gfn_range(kvm, &post_set_range);
out_unlock:
+ kvm->attribute_change_in_progress = false;
mutex_unlock(&kvm->slots_lock);
return r;
diff --git a/virt/kvm/kvm_mm.h b/virt/kvm/kvm_mm.h
index 715f19669d01f..5a53d888e4b18 100644
--- a/virt/kvm/kvm_mm.h
+++ b/virt/kvm/kvm_mm.h
@@ -27,12 +27,22 @@ kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool interruptible,
void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm,
unsigned long start,
unsigned long end);
+
+void gfn_to_pfn_cache_invalidate_gfns_start(struct kvm *kvm,
+ gfn_t start,
+ gfn_t end);
#else
static inline void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm,
unsigned long start,
unsigned long end)
{
}
+
+static inline void gfn_to_pfn_cache_invalidate_gfns_start(struct kvm *kvm,
+ gfn_t start,
+ gfn_t end)
+{
+}
#endif /* HAVE_KVM_PFNCACHE */
#ifdef CONFIG_KVM_PRIVATE_MEM
diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index f0039efb9e1e3..6de934a8a153f 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -57,6 +57,43 @@ void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, unsigned long start,
spin_unlock(&kvm->gpc_lock);
}
+/*
+ * Identical to `gfn_to_pfn_cache_invalidate_start`, except based on gfns
+ * instead of uhvas.
+ */
+void gfn_to_pfn_cache_invalidate_gfns_start(struct kvm *kvm, gfn_t start, gfn_t end)
+{
+ struct gfn_to_pfn_cache *gpc;
+
+ spin_lock(&kvm->gpc_lock);
+ list_for_each_entry(gpc, &kvm->gpc_list, list) {
+ read_lock_irq(&gpc->lock);
+
+ /*
+ * uhva based gpcs must not be used with gmem enabled memslots
+ */
+ if (kvm_is_error_gpa(gpc->gpa)) {
+ read_unlock_irq(&gpc->lock);
+ continue;
+ }
+
+ if (gpc->valid && !is_error_noslot_pfn(gpc->pfn) &&
+ gpa_to_gfn(gpc->gpa) >= start && gpa_to_gfn(gpc->gpa) < end) {
+ read_unlock_irq(&gpc->lock);
+
+ write_lock_irq(&gpc->lock);
+ if (gpc->valid && !is_error_noslot_pfn(gpc->pfn) &&
+ gpa_to_gfn(gpc->gpa) >= start && gpa_to_gfn(gpc->gpa) < end)
+ gpc->valid = false;
+ write_unlock_irq(&gpc->lock);
+ continue;
+ }
+
+ read_unlock_irq(&gpc->lock);
+ }
+ spin_unlock(&kvm->gpc_lock);
+}
+
static bool kvm_gpc_is_valid_len(gpa_t gpa, unsigned long uhva,
unsigned long len)
{
@@ -141,6 +178,14 @@ static inline bool mmu_notifier_retry_cache(struct kvm *kvm, unsigned long mmu_s
if (kvm->mn_active_invalidate_count)
return true;
+ /*
+ * Similarly to the above, attribute_change_in_progress is set
+ * before gfn_to_pfn_cache_invalidate_start is called in
+ * kvm_vm_set_mem_attributes, and isn't cleared until after
+ * mmu_invalidate_seq is updated.
+ */
+ if (kvm->attribute_change_in_progress)
+ return true;
/*
* Ensure mn_active_invalidate_count is read before
* mmu_invalidate_seq. This pairs with the smp_wmb() in
--
2.46.0
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