From: Ben Gardon <bgardon@google.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>, Peter Xu <peterx@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Peter Shier <pshier@google.com>,
Peter Feiner <pfeiner@google.com>,
Junaid Shahid <junaids@google.com>,
Jim Mattson <jmattson@google.com>,
Yulei Zhang <yulei.kernel@gmail.com>,
Wanpeng Li <kernellwp@gmail.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Xiao Guangrong <xiaoguangrong.eric@gmail.com>,
Ben Gardon <bgardon@google.com>
Subject: [PATCH 20/24] kvm: x86/mmu: Add atomic option for setting SPTEs
Date: Tue, 12 Jan 2021 10:10:37 -0800 [thread overview]
Message-ID: <20210112181041.356734-21-bgardon@google.com> (raw)
In-Reply-To: <20210112181041.356734-1-bgardon@google.com>
In order to allow multiple TDP MMU operations to proceed in parallel,
there must be an option to modify SPTEs atomically so that changes are
not lost. Add that option to __tdp_mmu_set_spte and
__handle_changed_spte.
Reviewed-by: Peter Feiner <pfeiner@google.com>
Signed-off-by: Ben Gardon <bgardon@google.com>
---
arch/x86/kvm/mmu/tdp_mmu.c | 67 ++++++++++++++++++++++++++++++++------
1 file changed, 57 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 264594947c3b..1380ed313476 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -7,6 +7,7 @@
#include "tdp_mmu.h"
#include "spte.h"
+#include <asm/cmpxchg.h>
#include <trace/events/kvm.h>
#ifdef CONFIG_X86_64
@@ -226,7 +227,8 @@ static void tdp_mmu_free_sp_rcu_callback(struct rcu_head *head)
}
static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
- u64 old_spte, u64 new_spte, int level);
+ u64 old_spte, u64 new_spte, int level,
+ bool atomic);
static int kvm_mmu_page_as_id(struct kvm_mmu_page *sp)
{
@@ -320,15 +322,19 @@ static void tdp_mmu_unlink_page(struct kvm *kvm, struct kvm_mmu_page *sp,
*
* @kvm: kvm instance
* @pt: the page removed from the paging structure
+ * @atomic: Use atomic operations to clear the SPTEs in any disconnected
+ * pages of memory.
*
* Given a page table that has been removed from the TDP paging structure,
* iterates through the page table to clear SPTEs and free child page tables.
*/
-static void handle_disconnected_tdp_mmu_page(struct kvm *kvm, u64 *pt)
+static void handle_disconnected_tdp_mmu_page(struct kvm *kvm, u64 *pt,
+ bool atomic)
{
struct kvm_mmu_page *sp;
gfn_t gfn;
int level;
+ u64 *sptep;
u64 old_child_spte;
int i;
@@ -341,11 +347,17 @@ static void handle_disconnected_tdp_mmu_page(struct kvm *kvm, u64 *pt)
tdp_mmu_unlink_page(kvm, sp, atomic);
for (i = 0; i < PT64_ENT_PER_PAGE; i++) {
- old_child_spte = READ_ONCE(*(pt + i));
- WRITE_ONCE(*(pt + i), 0);
+ sptep = pt + i;
+
+ if (atomic) {
+ old_child_spte = xchg(sptep, 0);
+ } else {
+ old_child_spte = READ_ONCE(*sptep);
+ WRITE_ONCE(*sptep, 0);
+ }
handle_changed_spte(kvm, kvm_mmu_page_as_id(sp),
gfn + (i * KVM_PAGES_PER_HPAGE(level - 1)),
- old_child_spte, 0, level - 1);
+ old_child_spte, 0, level - 1, atomic);
}
kvm_flush_remote_tlbs_with_address(kvm, gfn,
@@ -362,12 +374,15 @@ static void handle_disconnected_tdp_mmu_page(struct kvm *kvm, u64 *pt)
* @old_spte: The value of the SPTE before the change
* @new_spte: The value of the SPTE after the change
* @level: the level of the PT the SPTE is part of in the paging structure
+ * @atomic: Use atomic operations to clear the SPTEs in any disconnected
+ * pages of memory.
*
* Handle bookkeeping that might result from the modification of a SPTE.
* This function must be called for all TDP SPTE modifications.
*/
static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
- u64 old_spte, u64 new_spte, int level)
+ u64 old_spte, u64 new_spte, int level,
+ bool atomic)
{
bool was_present = is_shadow_present_pte(old_spte);
bool is_present = is_shadow_present_pte(new_spte);
@@ -439,18 +454,50 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
*/
if (was_present && !was_leaf && (pfn_changed || !is_present))
handle_disconnected_tdp_mmu_page(kvm,
- spte_to_child_pt(old_spte, level));
+ spte_to_child_pt(old_spte, level), atomic);
}
static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
- u64 old_spte, u64 new_spte, int level)
+ u64 old_spte, u64 new_spte, int level,
+ bool atomic)
{
- __handle_changed_spte(kvm, as_id, gfn, old_spte, new_spte, level);
+ __handle_changed_spte(kvm, as_id, gfn, old_spte, new_spte, level,
+ atomic);
handle_changed_spte_acc_track(old_spte, new_spte, level);
handle_changed_spte_dirty_log(kvm, as_id, gfn, old_spte,
new_spte, level);
}
+/*
+ * tdp_mmu_set_spte_atomic - Set a TDP MMU SPTE atomically and handle the
+ * associated bookkeeping
+ *
+ * @kvm: kvm instance
+ * @iter: a tdp_iter instance currently on the SPTE that should be set
+ * @new_spte: The value the SPTE should be set to
+ * Returns: true if the SPTE was set, false if it was not. If false is returned,
+ * this function will have no side-effects.
+ */
+static inline bool tdp_mmu_set_spte_atomic(struct kvm *kvm,
+ struct tdp_iter *iter,
+ u64 new_spte)
+{
+ u64 *root_pt = tdp_iter_root_pt(iter);
+ struct kvm_mmu_page *root = sptep_to_sp(root_pt);
+ int as_id = kvm_mmu_page_as_id(root);
+
+ kvm_mmu_lock_assert_held_shared(kvm);
+
+ if (cmpxchg64(iter->sptep, iter->old_spte, new_spte) != iter->old_spte)
+ return false;
+
+ handle_changed_spte(kvm, as_id, iter->gfn, iter->old_spte, new_spte,
+ iter->level, true);
+
+ return true;
+}
+
+
/*
* __tdp_mmu_set_spte - Set a TDP MMU SPTE and handle the associated bookkeeping
* @kvm: kvm instance
@@ -480,7 +527,7 @@ static inline void __tdp_mmu_set_spte(struct kvm *kvm, struct tdp_iter *iter,
WRITE_ONCE(*iter->sptep, new_spte);
__handle_changed_spte(kvm, as_id, iter->gfn, iter->old_spte, new_spte,
- iter->level);
+ iter->level, false);
if (record_acc_track)
handle_changed_spte_acc_track(iter->old_spte, new_spte,
iter->level);
--
2.30.0.284.gd98b1dd5eaa7-goog
next prev parent reply other threads:[~2021-01-12 18:14 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-12 18:10 [PATCH 00/24] Allow parallel page faults with TDP MMU Ben Gardon
2021-01-12 18:10 ` [PATCH 01/24] locking/rwlocks: Add contention detection for rwlocks Ben Gardon
2021-01-12 18:10 ` [PATCH 02/24] sched: Add needbreak " Ben Gardon
2021-01-12 18:10 ` [PATCH 03/24] sched: Add cond_resched_rwlock Ben Gardon
2021-01-12 18:10 ` [PATCH 04/24] kvm: x86/mmu: change TDP MMU yield function returns to match cond_resched Ben Gardon
2021-01-20 18:38 ` Sean Christopherson
2021-01-21 20:22 ` Paolo Bonzini
2021-01-26 14:11 ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 05/24] kvm: x86/mmu: Fix yielding in TDP MMU Ben Gardon
2021-01-20 19:28 ` Sean Christopherson
2021-01-22 1:06 ` Ben Gardon
2021-01-12 18:10 ` [PATCH 06/24] kvm: x86/mmu: Skip no-op changes in TDP MMU functions Ben Gardon
2021-01-20 19:51 ` Sean Christopherson
2021-01-25 23:51 ` Ben Gardon
2021-01-12 18:10 ` [PATCH 07/24] kvm: x86/mmu: Add comment on __tdp_mmu_set_spte Ben Gardon
2021-01-26 14:13 ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 08/24] kvm: x86/mmu: Add lockdep when setting a TDP MMU SPTE Ben Gardon
2021-01-20 19:58 ` Sean Christopherson
2021-01-26 14:13 ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 09/24] kvm: x86/mmu: Don't redundantly clear TDP MMU pt memory Ben Gardon
2021-01-20 20:06 ` Sean Christopherson
2021-01-26 14:14 ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 10/24] kvm: x86/mmu: Factor out handle disconnected pt Ben Gardon
2021-01-20 20:30 ` Sean Christopherson
2021-01-26 14:14 ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 11/24] kvm: x86/mmu: Put TDP MMU PT walks in RCU read-critical section Ben Gardon
2021-01-20 22:19 ` Sean Christopherson
2021-01-12 18:10 ` [PATCH 12/24] kvm: x86/kvm: RCU dereference tdp mmu page table links Ben Gardon
2021-01-22 18:32 ` Sean Christopherson
2021-01-26 18:17 ` Ben Gardon
2021-01-12 18:10 ` [PATCH 13/24] kvm: x86/mmu: Only free tdp_mmu pages after a grace period Ben Gardon
2021-01-12 18:10 ` [PATCH 14/24] kvm: mmu: Wrap mmu_lock lock / unlock in a function Ben Gardon
2021-01-12 18:10 ` [PATCH 15/24] kvm: mmu: Wrap mmu_lock cond_resched and needbreak Ben Gardon
2021-01-21 0:19 ` Sean Christopherson
2021-01-21 20:17 ` Paolo Bonzini
2021-01-26 14:38 ` Paolo Bonzini
2021-01-26 17:47 ` Ben Gardon
2021-01-26 17:55 ` Paolo Bonzini
2021-01-26 18:11 ` Ben Gardon
2021-01-26 20:47 ` Paolo Bonzini
2021-01-27 20:08 ` Ben Gardon
2021-01-27 20:55 ` Paolo Bonzini
2021-01-27 21:20 ` Ben Gardon
2021-01-28 8:18 ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 16/24] kvm: mmu: Wrap mmu_lock assertions Ben Gardon
2021-01-26 14:29 ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 17/24] kvm: mmu: Move mmu_lock to struct kvm_arch Ben Gardon
2021-01-12 18:10 ` [PATCH 18/24] kvm: x86/mmu: Use an rwlock for the x86 TDP MMU Ben Gardon
2021-01-21 0:45 ` Sean Christopherson
2021-01-12 18:10 ` [PATCH 19/24] kvm: x86/mmu: Protect tdp_mmu_pages with a lock Ben Gardon
2021-01-21 19:22 ` Sean Christopherson
2021-01-21 21:32 ` Sean Christopherson
2021-01-26 14:27 ` Paolo Bonzini
2021-01-26 21:47 ` Ben Gardon
2021-01-26 22:02 ` Sean Christopherson
2021-01-26 22:09 ` Sean Christopherson
2021-01-27 12:40 ` Paolo Bonzini
2021-01-26 13:37 ` Paolo Bonzini
2021-01-26 21:07 ` Ben Gardon
2021-01-12 18:10 ` Ben Gardon [this message]
2021-01-26 14:21 ` [PATCH 20/24] kvm: x86/mmu: Add atomic option for setting SPTEs Paolo Bonzini
2021-01-12 18:10 ` [PATCH 21/24] kvm: x86/mmu: Use atomic ops to set SPTEs in TDP MMU map Ben Gardon
2021-01-12 18:10 ` [PATCH 22/24] kvm: x86/mmu: Flush TLBs after zap in TDP MMU PF handler Ben Gardon
2021-01-21 0:05 ` Sean Christopherson
2021-01-12 18:10 ` [PATCH 23/24] kvm: x86/mmu: Freeze SPTEs in disconnected pages Ben Gardon
2021-01-12 18:10 ` [PATCH 24/24] kvm: x86/mmu: Allow parallel page faults for the TDP MMU Ben Gardon
2021-01-21 0:55 ` Sean Christopherson
2021-01-26 21:57 ` Ben Gardon
2021-01-27 17:14 ` Sean Christopherson
2021-01-26 13:37 ` Paolo Bonzini
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