linux-kernel - [PATCH 07/13] RISC-V: KVM: Don't flush TLB in gstage_set

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250605061458.196003-8-apatel@ventanamicro.com>
Date: Thu,  5 Jun 2025 11:44:52 +0530
From: Anup Patel <apatel@...tanamicro.com>
To: Atish Patra <atish.patra@...ux.dev>
Cc: Palmer Dabbelt <palmer@...belt.com>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Alexandre Ghiti <alex@...ti.fr>,
	Andrew Jones <ajones@...tanamicro.com>,
	Anup Patel <anup@...infault.org>,
	kvm@...r.kernel.org,
	kvm-riscv@...ts.infradead.org,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Anup Patel <apatel@...tanamicro.com>
Subject: [PATCH 07/13] RISC-V: KVM: Don't flush TLB in gstage_set_pte() when PTE is unchanged

The gstage_set_pte() should flush remote TLB only when a leaf PTE
changes so that unnecessary remote TLB flushes can be avoided.

Signed-off-by: Anup Patel <apatel@...tanamicro.com>
---
 arch/riscv/kvm/mmu.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index 1087ea74567b..d4eb1999b794 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -167,9 +167,11 @@ static int gstage_set_pte(struct kvm *kvm, u32 level,
 		ptep = &next_ptep[gstage_pte_index(addr, current_level)];
 	}
 
-	set_pte(ptep, *new_pte);
-	if (gstage_pte_leaf(ptep))
-		gstage_remote_tlb_flush(kvm, current_level, addr);
+	if (pte_val(*ptep) != pte_val(*new_pte)) {
+		set_pte(ptep, *new_pte);
+		if (gstage_pte_leaf(ptep))
+			gstage_remote_tlb_flush(kvm, current_level, addr);
+	}
 
 	return 0;
 }
-- 
2.43.0