From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f73.google.com (mail-pj1-f73.google.com [209.85.216.73]) (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 52C2A33688A for ; Thu, 5 Mar 2026 01:49:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772675368; cv=none; b=sDMAEcv0ajq/6tn+B5iYQ2sluUMK3pyKxY9wi5sUjsEZNqO0Abs4vDDQ+MjfNWDR5XiTsFC/IG56+0CvZMx+qa0JiyPxkNhwa0BOQ5iqqEUtnqIXpxPXKUjJKRXrRXYoLHFeHG5NWduBe21/kRdJDdMlPMi89iTbfz5cyJjKKKs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772675368; c=relaxed/simple; bh=QsGvvZgBswGhh6q51RcmfFvMflu6GVSHKIUeSa47SmI=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=NlWKO7u53/f0fFQua46UA5Pi4TzhSLdfZXS2iK242xw5FlxNtwWovm6bchp78QWOdTcr7d6HNmUK8MKoC4+fnp46AoGVVbE1H67zyhMXkf7fPGjwiRi6GHfkafG8YWvrbmshmEZq0frBwHs+NdxLp3SoGzEahDrXFYf+uJ2qQ/g= 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=GMtJkjHj; arc=none smtp.client-ip=209.85.216.73 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="GMtJkjHj" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-359887aece0so4501689a91.1 for ; Wed, 04 Mar 2026 17:49:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1772675367; x=1773280167; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=0nBxGvrjSGaqGUT1HQmx6sXgHlT0kR2meTAAgdjspys=; b=GMtJkjHjCNi+MC76KEjLVhUOyLy4LUXNE+mYDAdJgBb1atqYLXQxj1zl1UXzZLEbJC YPCdEHGcTLNJVi7P22lV+IvJc0THpLOu9OqiIzsS+giDNP1nwHPgVNYxAOGgYf+mhA19 kB93S7zGU4FLlxm69lnHSKr/O6hAgREwxtuTh93yJR69384QKHoc5JfCjw8C39ZRKoyD DzY9gTGFDAE1X9bMpxFGFMR/awvGKyDUC8mzV/MVeLCHjefKfdIscBmzaXF8UCIIiCLQ zS7vK+jOdY5O9/R9GpRjQnu7lJSUczvBb/mF40uv2OpKm2R3A5fBuXvZZkjQUvIhIRWo P2YQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1772675367; x=1773280167; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=0nBxGvrjSGaqGUT1HQmx6sXgHlT0kR2meTAAgdjspys=; b=DqsUAJdmD8WHJPLI4MaagGgLPwUJmUe3bJ7so45KMMCpt1jd7k22u2KCdxvnxfj7r5 Du5nK467P3nTYkLuEORmqasKu2m6KukLX4SPf8HunD6jCtkBJJ8EdpJRDE/962vbd5M2 zcBI4ryoV86PObw9ccPBRacw59Qz7PPJWM8oZPubdGUE8W58nuGQu+OXtOtEQd66OI8W tPKV5B3fks5J8I8WjFpni2q+vdnuZMj8CYL8/RoHaH2xiN3j6XnER/cVz5zkpBBRLpOs ybaJia5hhtv0oDV4/vkK+w9HRCrpy7s2FJYI36dOfzJI2f16F08PcgpFsNHeMup/PrW/ +M4w== X-Forwarded-Encrypted: i=1; AJvYcCWhmLYHqU1H43Z/5P7OAPssHP36MyOzC91N3OCMpTshbU7F78Z/Eu2NreN5duA9OjaVnjMoqzXq1BDOerE=@vger.kernel.org X-Gm-Message-State: AOJu0YwxR+oPNDmk9XXguOT+noNlbxH9EouT+OQeVUh1lthk5j331dOf DB86jtBoHXberQDu5Yjqh+tquL6zVkVH5Xs2YbBUcspeiNiKdakfhMUESeD8ulvjLvAToPrEhjf Ov6MHGg== X-Received: from pgbck19.prod.google.com ([2002:a05:6a02:913:b0:c73:8240:7190]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a21:498:b0:36a:d3c9:efa5 with SMTP id adf61e73a8af0-3982e1b3ed0mr3468683637.52.1772675366351; Wed, 04 Mar 2026 17:49:26 -0800 (PST) Date: Wed, 4 Mar 2026 17:49:24 -0800 In-Reply-To: <20260112235408.168200-3-chang.seok.bae@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260112235408.168200-1-chang.seok.bae@intel.com> <20260112235408.168200-3-chang.seok.bae@intel.com> Message-ID: Subject: Re: [PATCH v2 02/16] KVM: x86: Refactor GPR accessors to differentiate register access types From: Sean Christopherson To: "Chang S. Bae" Cc: pbonzini@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, chao.gao@intel.com Content-Type: text/plain; charset="us-ascii" On Mon, Jan 12, 2026, Chang S. Bae wrote: > Refactor the GPR accessors to introduce internal helpers to distinguish > between legacy and extended GPRs. Add CONFIG_KVM_APX to selectively > enable EGPR support. Why? If we really want to make this code efficient, use static calls to wire things up if and only if APX is fully supported. > +#ifdef CONFIG_KVM_APX > +static unsigned long kvm_read_egpr(int reg) > +{ > + return 0; > +} > + > +static void kvm_write_egpr(int reg, unsigned long data) > +{ > +} > + > +unsigned long kvm_gpr_read_raw(struct kvm_vcpu *vcpu, int reg) > +{ > + switch (reg) { > + case VCPU_REGS_RAX ... VCPU_REGS_R15: > + return kvm_register_read_raw(vcpu, reg); > + case VCPU_XREG_R16 ... VCPU_XREG_R31: > + return kvm_read_egpr(reg); > + default: > + WARN_ON_ONCE(1); > + } > + > + return 0; > +} > +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_gpr_read_raw); > + > +void kvm_gpr_write_raw(struct kvm_vcpu *vcpu, int reg, unsigned long val) > +{ > + switch (reg) { > + case VCPU_REGS_RAX ... VCPU_REGS_R15: > + kvm_register_write_raw(vcpu, reg, val); > + break; > + case VCPU_XREG_R16 ... VCPU_XREG_R31: > + kvm_write_egpr(reg, val); > + break; > + default: > + WARN_ON_ONCE(1); > + } > +} > +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_gpr_write_raw); > +#endif Has anyone done analysis to determine if KVM's currently inlining of kvm_register_read() and kvm_register_write() is actually a net positive? I.e. can we just cut over to non-inline functions with static calls?