kvm.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Michael Roth <michael.roth@amd.com>,
	Binbin Wu <binbin.wu@linux.intel.com>
Subject: [PATCH 07/13] KVM: x86/mmu: Track PRIVATE impact on hugepage mappings for all memslots
Date: Thu, 21 Sep 2023 13:33:24 -0700	[thread overview]
Message-ID: <20230921203331.3746712-8-seanjc@google.com> (raw)
In-Reply-To: <20230921203331.3746712-1-seanjc@google.com>

Track the effects of private attributes on potential hugepage mappings if
the VM supports private memory, i.e. even if the target memslot can only
ever be mapped shared.  If userspace configures a chunk of memory as
private, KVM must not allow that memory to be mapped shared regardless of
whether or not the *current* memslot can be mapped private.  E.g. if the
guest accesses a private range using a shared memslot, then KVM must exit
to userspace.

Fixes: 5bb0b4e162d1 ("KVM: x86: Disallow hugepages when memory attributes are mixed")
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/mmu/mmu.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 269d4dc47c98..148931cf9dba 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -7314,10 +7314,12 @@ bool kvm_arch_post_set_memory_attributes(struct kvm *kvm,
 	lockdep_assert_held(&kvm->slots_lock);
 
 	/*
-	 * KVM x86 currently only supports KVM_MEMORY_ATTRIBUTE_PRIVATE, skip
-	 * the slot if the slot will never consume the PRIVATE attribute.
+	 * Calculate which ranges can be mapped with hugepages even if the slot
+	 * can't map memory PRIVATE.  KVM mustn't create a SHARED hugepage over
+	 * a range that has PRIVATE GFNs, and conversely converting a range to
+	 * SHARED may now allow hugepages.
 	 */
-	if (!kvm_slot_can_be_private(slot))
+	if (WARN_ON_ONCE(!kvm_arch_has_private_mem(kvm)))
 		return false;
 
 	/*
@@ -7372,7 +7374,7 @@ void kvm_mmu_init_memslot_memory_attributes(struct kvm *kvm,
 {
 	int level;
 
-	if (!kvm_slot_can_be_private(slot))
+	if (!kvm_arch_has_private_mem(kvm))
 		return;
 
 	for (level = PG_LEVEL_2M; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) {
-- 
2.42.0.515.g380fc7ccd1-goog


  parent reply	other threads:[~2023-09-21 20:56 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-21 20:33 [PATCH 00/13] KVM: guest_memfd fixes Sean Christopherson
2023-09-21 20:33 ` [PATCH 01/13] KVM: Assert that mmu_invalidate_in_progress *never* goes negative Sean Christopherson
2023-09-21 20:33 ` [PATCH 02/13] KVM: Actually truncate the inode when doing PUNCH_HOLE for guest_memfd Sean Christopherson
2023-09-21 20:33 ` [PATCH 03/13] KVM: WARN if *any* MMU invalidation sequence doesn't add a range Sean Christopherson
2023-09-21 20:33 ` [PATCH 04/13] KVM: WARN if there are danging MMU invalidations at VM destruction Sean Christopherson
2023-09-27  3:16   ` Binbin Wu
2023-09-28 18:11     ` Sean Christopherson
2023-09-21 20:33 ` [PATCH 05/13] KVM: Fix MMU invalidation bookkeeping in guest_memfd Sean Christopherson
2023-09-21 20:33 ` [PATCH 06/13] KVM: Disallow hugepages for incompatible gmem bindings, but let 'em succeed Sean Christopherson
2023-09-22 22:42   ` Michael Roth
2023-09-28 18:31     ` Sean Christopherson
2023-10-02 15:53       ` Michael Roth
2023-10-02 16:49         ` Sean Christopherson
2023-09-21 20:33 ` Sean Christopherson [this message]
2023-09-27  6:01   ` [PATCH 07/13] KVM: x86/mmu: Track PRIVATE impact on hugepage mappings for all memslots Binbin Wu
2023-09-27 14:25     ` Sean Christopherson
2023-09-21 20:33 ` [PATCH 08/13] KVM: x86/mmu: Zap shared-only memslots when private attribute changes Sean Christopherson
2023-09-21 20:33 ` [PATCH 09/13] KVM: Always add relevant ranges to invalidation set when changing attributes Sean Christopherson
2023-09-21 20:33 ` [PATCH 10/13] KVM: x86/mmu: Drop repeated add() of to-be-invalidated range Sean Christopherson
2023-09-21 20:33 ` [PATCH 11/13] KVM: selftests: Refactor private mem conversions to prep for punch_hole test Sean Christopherson
2023-09-21 20:33 ` [PATCH 12/13] KVM: selftests: Add a "pure" PUNCH_HOLE on guest_memfd testcase Sean Christopherson
2023-09-21 20:33 ` [PATCH 13/13] KVM: Rename guest_mem.c to guest_memfd.c Sean Christopherson
2023-09-29  2:22 ` [PATCH 00/13] KVM: guest_memfd fixes Sean Christopherson

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20230921203331.3746712-8-seanjc@google.com \
    --to=seanjc@google.com \
    --cc=binbin.wu@linux.intel.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=michael.roth@amd.com \
    --cc=pbonzini@redhat.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).