From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (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 6781D4DC527 for ; Wed, 3 Jun 2026 23:07:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780528045; cv=none; b=i9Pibl0bH28fopLsQF9aVYXd262N/RvIiUbz9SY8oFi6bkmn6ZLUXOJiIyMFnWcw/J4snJX200brMql2rOGOhUVg+ZA7Ev74DyGz8whTIQcqw7e4G1Na/kcuP3C8toCDdG1dqGflHnIPs8HJcODyx2AYhFvsVEOCchWbzLHTMw4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780528045; c=relaxed/simple; bh=zvLZFUC8kt5SYBz7pPfHBF6oXjTl1YD9FgGc8bCW94g=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=Jvdl4mIrxalRZntW5EsH99cb30WH6gSlp7EXqP0j/vfpbz/oyW/+Tr9iYd2tlwevMQZjigDbDSFD8Pal/p93vy/89BvXCIO+O7j3iDjkXEkhKEMb2/TlCFiijM/UtanVC8LP+SFUQyvMZgcYloPgKoGrPTa6ozayTqZ4EvsG4cQ= 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=TuksNok4; arc=none smtp.client-ip=209.85.214.201 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="TuksNok4" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-2bf1845bddfso978625ad.1 for ; Wed, 03 Jun 2026 16:07:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1780528043; x=1781132843; 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=J9jXkbLbsiQYLu/uZAeAeFQEm+TiK4gDJq2dRu+/ibQ=; b=TuksNok4JVdeY3MpGUb4579U+Brv5hK/Ue0M+wQBQefDQJSGxV4k4ztYSxru2Qf0Qd fN7tbdRd3YpTTCtUzllkLt2qDO7dQ/9AMfknAdAdyAdBhw1pmKwQA5XXBWRFgivkUo9y uWx6EzBvsF8fZ6QWlpvYfn+OFJ/uMmxuWfquitKaKm0OisaAMYeYTeY8fLPcyW7td6+f QSBMKwEl/G5a2qGske4xBaWDcS1lWk/9e3n+INv8/tmtqaB6N3uy0H1eOkzg0pPG09ZP J/W2hsr2x9MrgewRbBhdImD52USdE0lJXwMZuYIhyG1zwGSGCNFb2CYP6CztdY//6nn3 Iciw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780528043; x=1781132843; 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=J9jXkbLbsiQYLu/uZAeAeFQEm+TiK4gDJq2dRu+/ibQ=; b=cOSzkFyHp1ppB/iJ5nqqWEE+1u6S86qRqqrDMKsvcnE6/U0JWpqgPXv6k8Ilru31BB EUebvQMA2DW21idYvCJXjDfsd4Ego9X2k8/qnh4cU2YdMsUF7VxslSpsnXo+wgzmI3zD H2kjWof9xivCGLhrW/ERzVtDroXzwk5lTutOqqgoVUaD34o08+IMFxAhR+b74axbWxRz wPQMxiwX8eTq8L1SSDBNWi5vbHz2gGVZjCzbXbEYO2Udou079iXXqZywj0kWyPd1b4cg ey3CRXrspMYX47jk/5eJLL2LraaBCovI6VG4BoqTFnK7QmCDRNBTa3u1cmU4LPrP+ndG znGw== X-Forwarded-Encrypted: i=1; AFNElJ8OvFooe2VAz6tbElaJj3SNcVgNo/jUBRtqapFMh/0CY9Ix9IWR308FSEuSdUhEcbzZ0etzwg0Pji6EQHA=@vger.kernel.org X-Gm-Message-State: AOJu0YyvD0y3/WOBMP7LcnzyIRL9KfrFq55bAJjx8NDDGd5PybWQlMWt qOmm37bPOpSQu9a6GVIkPOukEUhMBG04UQ8TudebG3FG6rm2jP3ADW1k3NGoan9YkHIgVmaER2H tNs6/ZQ== X-Received: from plble15.prod.google.com ([2002:a17:902:fb0f:b0:2ba:39b8:446f]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:234c:b0:2bc:eea4:83c3 with SMTP id d9443c01a7336-2c163fa4889mr55162265ad.25.1780528043207; Wed, 03 Jun 2026 16:07:23 -0700 (PDT) Reply-To: Sean Christopherson Date: Wed, 3 Jun 2026 16:07:15 -0700 In-Reply-To: <20260603230718.1733483-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260603230718.1733483-1-seanjc@google.com> X-Mailer: git-send-email 2.54.0.1032.g2f8565e1d1-goog Message-ID: <20260603230718.1733483-4-seanjc@google.com> Subject: [PATCH v2 3/6] KVM: x86: Manually check DR4/5 write values to fix SVM intercept priority From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, "=?UTF-8?q?Carlos=20L=C3=B3pez?=" Content-Type: text/plain; charset="UTF-8" Manually (pre)check the values being written to DR4/5, i.e. the DR6/DR7 aliases, instead of relying on ->set_dr() => kvm_set_dr() to signal a #GP. SVM unfortunately prioritizes all exceptions over an instruction intercept, i.e. nSVM is relying on the emulator to perform *all* exception checks prior to attempting to execute the instruction. Fixes: 3b88e41a4134 ("KVM: SVM: Add intercept check for accessing dr registers") Signed-off-by: Sean Christopherson --- arch/x86/kvm/emulate.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 4484c5fa19e3..a1bccab0eefe 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -3853,15 +3853,23 @@ static int check_dr_read(struct x86_emulate_ctxt *ctxt) static int check_dr_write(struct x86_emulate_ctxt *ctxt) { u64 new_val = ctxt->src.val64; - int dr = ctxt->modrm_reg; int rc; rc = check_dr_read(ctxt); if (rc != X86EMUL_CONTINUE) return rc; - if ((dr == 6 || dr == 7) && (new_val & 0xffffffff00000000ULL)) - return emulate_gp(ctxt, 0); + switch (ctxt->modrm_reg) { + case 4: + case 5: + case 6: + case 7: + if (new_val & 0xffffffff00000000ULL) + return emulate_gp(ctxt, 0); + break; + default: + break; + } return X86EMUL_CONTINUE; } -- 2.54.0.1032.g2f8565e1d1-goog