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From: "Shahin, Md Shahadat Hossain" <shahinmd@amazon.de>
To: "kvm@vger.kernel.org" <kvm@vger.kernel.org>
Cc: "Szczepanek, Bartosz" <bsz@amazon.de>,
	"seanjc@google.com" <seanjc@google.com>,
	"bgardon@google.com" <bgardon@google.com>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>
Subject: [PATCH v2] kvm/x86: Fix 'lpages' kvm stat for TDM MMU
Date: Fri, 30 Apr 2021 11:52:31 +0000	[thread overview]
Message-ID: <1619783551459.35424@amazon.de> (raw)

Large pages not being created properly may result in increased memory
access time. The 'lpages' kvm stat used to keep track of the current
number of large pages in the system, but with TDP MMU enabled the stat
is not showing the correct number.

This patch extends the lpages counter to cover the TDP case.

Signed-off-by: Md Shahadat Hossain Shahin <shahinmd@amazon.de>
Cc: Bartosz Szczepanek <bsz@amazon.de>
 arch/x86/kvm/mmu/tdp_mmu.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index bc1283ed4db6..f89a140b8dea 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -240,6 +240,13 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
 	if (old_spte == new_spte)
+	if (is_large_pte(old_spte) != is_large_pte(new_spte)) {
+		if (is_large_pte(old_spte))
+			atomic64_sub(1, (atomic64_t*)&kvm->stat.lpages);
+		else
+			atomic64_add(1, (atomic64_t*)&kvm->stat.lpages);
+	}
 	 * The only times a SPTE should be changed from a non-present to
 	 * non-present state is when an MMIO entry is installed/modified/

Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879

             reply	other threads:[~2021-04-30 11:52 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-30 11:52 Shahin, Md Shahadat Hossain [this message]
2021-05-03 16:25 ` [PATCH v2] kvm/x86: Fix 'lpages' kvm stat for TDM MMU Ben Gardon

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