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 C7F1D3D88E4 for ; Fri, 12 Jun 2026 23:01:21 +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=1781305282; cv=none; b=lp+pfUuwnwLC0/Hbx7g7mS8cOMpnSv99CAnS8hYqo11EHiMoOG25gJ7PR9zlE61rp4fHn9g/gjAWuhMOkES5tli0vdp9GNlP/LmMfI15V1WgghGs0EONedyZL2BT+HM/4S0W4+M2UZYNYjRHQ6JoqgF4FrgqegRN+J/PKC1Zn1A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781305282; c=relaxed/simple; bh=9EfiWtDfFbNqVVMC/Fao29oObDR7IDsnb1QmgG5u62Y=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=OPWF+iG6tU7j3+fsr9/aZLsDn/4fXik0qbz/JTX9oZpvq226vDPKJdgJCogrdfPNR07HrXexjwPnatk5TzHORk6G2Co3JAsspSrWCosZmCTNrAjLCTm8LB1eZsoXJMpQhyVsznFwGqnz+uubSGhYoCOpArE/IJof4FwMrli2SAM= 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=ko1W5laH; 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="ko1W5laH" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-2bd04e4fe3dso35326445ad.3 for ; Fri, 12 Jun 2026 16:01:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1781305281; x=1781910081; 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=S0l+jwQAw9AdDhvDUdYHfGnTWpsYaOO/BEuKKirwcds=; b=ko1W5laHM+rC7B3bjGIMfZ/woF0zC7A4+iBxfun9bN49HND6K0RtkC9B9stTjcMeud ykfTFC1OBQd7cDkhhINqE/qSlc+rhml07jD8HBqJBo5lJE1C1Q5M4DcIfZF99SFP51jg E8Tg0Gdt63rylpKRPHCmaVZVaAtSbyG9vOXRedWnxEYVLxbq21HqPHgbKMw3W8Uoerln YQ3ZXuaE5cV1k3h9PJ08HFCpjjVv+csC7OG3m2tp9m/nezsKKwZ5qVdSiUF/BkGPLTH+ p4nOhlCtmezR/z7SAk4jwJSlHyMWTMmlL1qM7xARqCGM3qTwYcnDUASshrfSFdrm9/RA zn2w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1781305281; x=1781910081; 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=S0l+jwQAw9AdDhvDUdYHfGnTWpsYaOO/BEuKKirwcds=; b=agDbYkaEPFw9aAy7fR093T1GtKM20c/wIRVGLQVZ7L3qvo+lmFrwgXVW3JrQn4/mm6 2qOZBN52X0AfpXDc0/Tbum9lkkvp3BYnOHyOekdbm5maiEGDi66pKwElG3dR/AbAbf5g LtdeBCtzI1RBViVfbstz4EtJBOZSwZ1kiWGZYxZCruqoHCoKMmQT4PldvFmT5VGF3iCS 0b8nn1Fiu/GvlECcVmNhT08HToun9Jy9NZluUchi/EBAcMMh8EHPnyGaMq5VWQOwouSh cfMv7LJCav0flz5d3MkdB0a8zijkG2jsfBWNFm+eVD5e7FV6XmCbWYM9hYFdwUlcZekh 9zsw== X-Forwarded-Encrypted: i=1; AFNElJ+GEVhkqpEYBindIqOv7Ypagjs24wBOysaWqKKgvXZzQeb6v6+FfWxmRxH7+UxNVB6t1ffu9NnAN2tHcgU=@vger.kernel.org X-Gm-Message-State: AOJu0YyfqlnEkvrVEbxQxdYXH/d/+Bo5mkJ9OuxEtjlQqpW34BNcl45G TsrHHl4NCYrvFBvEEtyXW3vtm35lYSMkeuSvtzFSPmdCPRgR6xFzoS9DwsQ/TkpDuOh192BraAZ K3aG2nw== X-Received: from plnd4.prod.google.com ([2002:a17:903:1984:b0:2c0:bff2:48e4]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:cf4b:b0:2c0:c262:b91f with SMTP id d9443c01a7336-2c4109ed6cemr57967345ad.8.1781305280985; Fri, 12 Jun 2026 16:01:20 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 12 Jun 2026 16:01:08 -0700 In-Reply-To: <20260612230113.684301-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260612230113.684301-1-seanjc@google.com> X-Mailer: git-send-email 2.54.0.1136.gdb2ca164c4-goog Message-ID: <20260612230113.684301-4-seanjc@google.com> Subject: [PATCH v3 3/8] 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?=" , "Maciej W . Rozycki" 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; } -- 2.54.0.1136.gdb2ca164c4-goog