From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 62CF13F88B8 for ; Fri, 29 May 2026 16:51:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780073493; cv=none; b=V9Y8JDdqYWZpLxoFU/PQ8gaPf6soHA9oo6TEnQtnGqb9Q6d7hkewlUZrRIVT4hCkcDQ+4MYThlEkZYX8Aw/SJ4A+UkDVXrIDajuT+ZGBK3LvzDv0A/RfMoGG+v2y86rAzOGsBZHP0e+33sk2wMj24R2NlvPJT8vtXgy3p8TXWcU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780073493; c=relaxed/simple; bh=7d+dI7BCOXsb/xg7q8MDnqPJ4olf9QKcYi3J2vHMi8c=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=oiWchKjVAPXRQzUF3cVVcF+wEslNMr4gV+wH6K8xKbXKKD4dhx0jCX1F+2BZeKNXzizXqRK19z5XBTGLVWWLrDxO64ZRAHvr34nzA8ZNELESgJdR3gCEtKsB9n4lGPKO6vhilvquKqns16QmQu++WfNCto2DsxgZQLD8Dy3xu4E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=mkxs2vGk; arc=none smtp.client-ip=209.85.214.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="mkxs2vGk" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-2b99eb06178so68097885ad.2 for ; Fri, 29 May 2026 09:51:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1780073488; x=1780678288; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=eAHT4lc4Hf6k7nHbKC1TYzljr82cl9daWTb4LEaL2yg=; b=mkxs2vGk7xCUFt9gHfBFeTVpD5PFjVtmX7ppOpXaysIwVfyJ240XtUp6AEIp2sEFQk GnyJJofrBTxCatInbpkj6nG/neHVQDiYnQXeG3D0YH2y6E5j7zVeQf5cTwHn7YwXlLAM Um2nRqseJzOnV8gARZm6ZJzdmskn9SMZJ3i6gJ/pPkHoWyEF1kafECcghiwZpFVGgw3i kk6G9SmLmKR+nl0B9aajQEDX137ABD6FzyhRdE1aEEQm6t3TUo2LMyUxxrCRzpwEZI12 YLfGUDAKHCt8ygu6TUC5C09fBrv7ii/1mEIQaGt+l+NTIHiOpP0Wtd8rbe541tYJFqUM vz1A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780073488; x=1780678288; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=eAHT4lc4Hf6k7nHbKC1TYzljr82cl9daWTb4LEaL2yg=; b=kg0kJL+YFxolchPtRLRNnuveRIo1DJOXctT41Hy9BQZ5MjizxpCYiwELWMVsMwyc5b JuBqM9G4qg3qmNJ7dhlRG7R0rOSqrFfox6HzDNycK+UIlfiQsBfuym8fsJZVz2V72GE9 tR1lhzKC8YtgNMWnlRfM3dtFWdoWsE7FqZd3ICn7EYIah6ExuFVDiG7EvVHzlfXepNMv o6o1NAIJxcbROViK5Ncvs8H3MwwFVBl8UtEJFf6hNBc8r7+JpGZSGEC6zZ/TVtk1iX8y B+IfBCsDWj0nOAV7iFfvAwtVNYz+IRNAuoXxa/ZhIHk/VfpiBPSrne6Q0LE/B5/pJULe 4mvw== X-Forwarded-Encrypted: i=1; AFNElJ+Rp1UQ9DOzrUOqOhXMlEK8NLbwE7RR/lby92C/gUMs3rcmYLPped0+yL6qz4BOvw6E+ltY6C5WxTZNEGA=@vger.kernel.org X-Gm-Message-State: AOJu0YyRSQf3OcFH+KbaZzEiZA29spuqiW3RbVCq1GXgS8REsrCdp0gX 5ibQqqMQ8vr5zQzmEMTS2C+p+p7iO94vTOBv+xT3rsBEfPLjqP6eFFfIxEKzvQYH24rbpIqEllB EL4nVsA== X-Received: from plblo7.prod.google.com ([2002:a17:903:4347:b0:2bf:8db:4516]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:d58d:b0:2bf:21e6:baee with SMTP id d9443c01a7336-2bf36826736mr7842105ad.28.1780073488289; Fri, 29 May 2026 09:51:28 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 29 May 2026 09:50:59 -0700 In-Reply-To: <20260529165114.748639-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260529165114.748639-1-seanjc@google.com> X-Mailer: git-send-email 2.54.0.823.g6e5bcc1fc9-goog Message-ID: <20260529165114.748639-6-seanjc@google.com> Subject: [PATCH v2 05/20] KVM: Remove unnecessary IRQ disabling from GPC lock in pfncache.c From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini , David Woodhouse , Paul Durrant , Peter Zijlstra , Ingo Molnar , Will Deacon , Boqun Feng Cc: Waiman Long , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, David Woodhouse , Sebastian Andrzej Siewior , syzbot+208f7f3e5f59c11aeb90@syzkaller.appspotmail.com, Carsten Stollmaier Content-Type: text/plain; charset="UTF-8" From: David Woodhouse Now that all hardirq/atomic GPC users (xen_timer_callback, kvm_xen_set_evtchn_fast) use read_trylock() instead of read_lock(), no hardirq path ever holds the GPC rwlock. There is therefore no risk of deadlock between the write side and a hardirq reader, and no need to disable interrupts when taking the lock. Convert all read_lock_irq()/write_lock_irq() and their unlock counterparts to plain read_lock()/write_lock() in pfncache.c. Signed-off-by: David Woodhouse Signed-off-by: Sean Christopherson --- virt/kvm/pfncache.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c index 728d2c1b488a..70b102095173 100644 --- a/virt/kvm/pfncache.c +++ b/virt/kvm/pfncache.c @@ -29,12 +29,12 @@ void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, unsigned long start, spin_lock(&kvm->gpc_lock); list_for_each_entry(gpc, &kvm->gpc_list, list) { - read_lock_irq(&gpc->lock); + read_lock(&gpc->lock); /* Only a single page so no need to care about length */ if (gpc->valid && !is_error_noslot_pfn(gpc->pfn) && gpc->uhva >= start && gpc->uhva < end) { - read_unlock_irq(&gpc->lock); + read_unlock(&gpc->lock); /* * There is a small window here where the cache could @@ -44,15 +44,15 @@ void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, unsigned long start, * acquired. */ - write_lock_irq(&gpc->lock); + write_lock(&gpc->lock); if (gpc->valid && !is_error_noslot_pfn(gpc->pfn) && gpc->uhva >= start && gpc->uhva < end) gpc->valid = false; - write_unlock_irq(&gpc->lock); + write_unlock(&gpc->lock); continue; } - read_unlock_irq(&gpc->lock); + read_unlock(&gpc->lock); } spin_unlock(&kvm->gpc_lock); } @@ -184,7 +184,7 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc) mmu_seq = gpc->kvm->mmu_invalidate_seq; smp_rmb(); - write_unlock_irq(&gpc->lock); + write_unlock(&gpc->lock); /* * If the previous iteration "failed" due to an mmu_notifier @@ -225,7 +225,7 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc) goto out_error; } - write_lock_irq(&gpc->lock); + write_lock(&gpc->lock); /* * Other tasks must wait for _this_ refresh to complete before @@ -248,7 +248,7 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc) return 0; out_error: - write_lock_irq(&gpc->lock); + write_lock(&gpc->lock); return -EFAULT; } @@ -269,7 +269,7 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned l lockdep_assert_held(&gpc->refresh_lock); - write_lock_irq(&gpc->lock); + write_lock(&gpc->lock); if (!gpc->active) { ret = -EINVAL; @@ -355,7 +355,7 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned l unmap_old = (old_pfn != gpc->pfn); out_unlock: - write_unlock_irq(&gpc->lock); + write_unlock(&gpc->lock); if (unmap_old) gpc_unmap(old_pfn, old_khva); @@ -417,9 +417,9 @@ static int __kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned * refresh must not establish a mapping until the cache is * reachable by mmu_notifier events. */ - write_lock_irq(&gpc->lock); + write_lock(&gpc->lock); gpc->active = true; - write_unlock_irq(&gpc->lock); + write_unlock(&gpc->lock); } return __kvm_gpc_refresh(gpc, gpa, uhva); } @@ -458,7 +458,7 @@ void kvm_gpc_deactivate(struct gfn_to_pfn_cache *gpc) * must stall mmu_notifier events until all users go away, i.e. * until gpc->lock is dropped and refresh is guaranteed to fail. */ - write_lock_irq(&gpc->lock); + write_lock(&gpc->lock); gpc->active = false; gpc->valid = false; @@ -473,7 +473,7 @@ void kvm_gpc_deactivate(struct gfn_to_pfn_cache *gpc) old_pfn = gpc->pfn; gpc->pfn = KVM_PFN_ERR_FAULT; - write_unlock_irq(&gpc->lock); + write_unlock(&gpc->lock); spin_lock(&kvm->gpc_lock); list_del(&gpc->list); -- 2.54.0.823.g6e5bcc1fc9-goog