From patchwork Thu Nov 28 00:43:43 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 13887466 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (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 7C4831A270 for ; Thu, 28 Nov 2024 00:43:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732754638; cv=none; b=VbFjjtc04we+lQleJlr7FJ54GJ3aRQx6XDSScB7Shjyt74gl+yDzS6RMUsQD9ildziL/FkqP+fp3ccy9q1rTxCOszo2R9MyoSJCZHl+YhMKcL2lr+FHNxSqcFVZhImU2XRAbCw5Gvo7BFm5Cg1bpjGAPTg7Bsaj8wijG9XEbGH4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732754638; c=relaxed/simple; bh=AEDUeCL/zaARx8onXji3t/YtfDw26liZdxyZL4gPBeI=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=VOLsNLLggXXPMAQR+cTB22xa1VKnqPdrxICBxJOQ3oyAERdy4WvXsO8+6mivB0k2I41BA603L2BvBxMm+favDvWhEHRoMZ0okYz2NjPMLqmoiXP0chK0vSqOS/yoSl8yX+hhgnuJm8DvhQHcW3NZ+Q+rP5wz1MqB4V/6Oz6odAA= 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=MZtoZRpu; arc=none smtp.client-ip=209.85.216.74 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="MZtoZRpu" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-2edeef8a994so339944a91.2 for ; Wed, 27 Nov 2024 16:43:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1732754636; x=1733359436; 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=b+5GMpw/w1WHRIobpEWm5+/qy2gHIU4YsE7Y113p5dg=; b=MZtoZRpu338MJJmHtfYKDG3uwOHPGZhCnZm8GIf4tqm7RH1/zF1uxd19ucKx+2kR7I Z2TZ0yj/J4FGEjMswLH5BOp1Jo9br5CPk3AfnAEK4fBNt0KLywDDACvH8iGZ2r+GHO1s AX8dNAqsPiFUnYjKSG2fObPhN+6HwSzLo3V9YGRk7t3hpxTbcRCzGI10T8V0moGMxqUA MQjVNzYVELrzaoWSGPH7KIH9i/BttK1uuMvWSwbQsA81SMvFPfm7g9njcYMj8Nrqur9C qV1tjaKctHyQecApKVZIsMMpIVF64gXGEHRp+GVZYA0PY0jLacygQGGqxyczhEAON5M2 afVA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1732754636; x=1733359436; 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=b+5GMpw/w1WHRIobpEWm5+/qy2gHIU4YsE7Y113p5dg=; b=bKzzlL6xvpXb8hU14RTn6+EKCnxYv0RWcY++tz9A3YRujXxjxvz30G7W3Ad9T3O4Kd xTiX2iBPEfZXoHjXihQyrisIQ1jgkXtb6Sp3IZ74xNkBZOFZwXmWyu/iIbzyymmCeY3I JPbAqDYYczmEvyrcxWc8ev+5LthxGuavN8sJwGh85cLusLsTGyfSkZqblmdDT6rg2C4O 1jrJObBD2AQEejRvUKKhtOU3kQmXZw0jKwMEySZXqwuNjQyVO3sexjgmhnY4cNHVFbH9 nxqBYvCqv4NF/fxd5r0MIQcP8LEqfIY53Vvo9CHgd16/a/vStXL88xGHDUfj0FnTjDdd KRTQ== X-Gm-Message-State: AOJu0YwcQ+8OsRQ1xj/Q6bCyajrhJjmL3NyIOKhWWZY5D1v14jXHmSW5 /JyjENYoddaXm7AZv5SrqycJBjKB6Tj6RsRgqEQzcaq+iQ5izkHyLbBAtxhz0Ud+MxiuqaqN5Ek d9A== X-Google-Smtp-Source: AGHT+IGosbHKAV+rkitlr6k2kWiYww6vT/dEz80J0WwFs8XqNGHk+Uosu6KGRZs/IjB6xkH6D7120BnwA0M= X-Received: from pjbli14.prod.google.com ([2002:a17:90b:48ce:b0:2e2:9f67:1ca3]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:48c1:b0:2ea:9f38:993c with SMTP id 98e67ed59e1d1-2ee08ecc4d9mr6651891a91.18.1732754635965; Wed, 27 Nov 2024 16:43:55 -0800 (PST) Reply-To: Sean Christopherson Date: Wed, 27 Nov 2024 16:43:43 -0800 In-Reply-To: <20241128004344.4072099-1-seanjc@google.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241128004344.4072099-1-seanjc@google.com> X-Mailer: git-send-email 2.47.0.338.g60cca15819-goog Message-ID: <20241128004344.4072099-6-seanjc@google.com> Subject: [PATCH v4 5/6] KVM: x86: Always complete hypercall via function callback From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Tom Lendacky , Binbin Wu , Isaku Yamahata , Kai Huang , Xiaoyao Li Finish "emulation" of KVM hypercalls by function callback, even when the hypercall is handled entirely within KVM, i.e. doesn't require an exit to userspace, and refactor __kvm_emulate_hypercall()'s return value to *only* communicate whether or not KVM should exit to userspace or resume the guest. (Ab)Use vcpu->run->hypercall.ret to propagate the return value to the callback, purely to avoid having to add a trampoline for every completion callback. Using the function return value for KVM's control flow eliminates the multiplexed return value, where '0' for KVM_HC_MAP_GPA_RANGE (and only that hypercall) means "exit to userspace". Note, the unnecessary extra indirect call and thus potential retpoline will be eliminated in the near future by converting the intermediate layer to a macro. Suggested-by: Binbin Wu Suggested-by: Kai Huang Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 29 ++++++++++++----------------- arch/x86/kvm/x86.h | 10 ++++++---- 2 files changed, 18 insertions(+), 21 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 11434752b467..39be2a891ab4 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -9982,10 +9982,11 @@ static int complete_hypercall_exit(struct kvm_vcpu *vcpu) return kvm_skip_emulated_instruction(vcpu); } -unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr, - unsigned long a0, unsigned long a1, - unsigned long a2, unsigned long a3, - int op_64_bit, int cpl) +int __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr, + unsigned long a0, unsigned long a1, + unsigned long a2, unsigned long a3, + int op_64_bit, int cpl, + int (*complete_hypercall)(struct kvm_vcpu *)) { unsigned long ret; @@ -10061,7 +10062,7 @@ unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr, vcpu->run->hypercall.flags |= KVM_EXIT_HYPERCALL_LONG_MODE; WARN_ON_ONCE(vcpu->run->hypercall.flags & KVM_EXIT_HYPERCALL_MBZ); - vcpu->arch.complete_userspace_io = complete_hypercall_exit; + vcpu->arch.complete_userspace_io = complete_hypercall; /* stat is incremented on completion. */ return 0; } @@ -10071,13 +10072,15 @@ unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr, } out: - return ret; + vcpu->run->hypercall.ret = ret; + complete_hypercall(vcpu); + return 1; } EXPORT_SYMBOL_GPL(__kvm_emulate_hypercall); int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) { - unsigned long nr, a0, a1, a2, a3, ret; + unsigned long nr, a0, a1, a2, a3; int op_64_bit; int cpl; @@ -10095,16 +10098,8 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) op_64_bit = is_64_bit_hypercall(vcpu); cpl = kvm_x86_call(get_cpl)(vcpu); - ret = __kvm_emulate_hypercall(vcpu, nr, a0, a1, a2, a3, op_64_bit, cpl); - if (nr == KVM_HC_MAP_GPA_RANGE && !ret) - /* MAP_GPA tosses the request to the user space. */ - return 0; - - if (!op_64_bit) - ret = (u32)ret; - kvm_rax_write(vcpu, ret); - - return kvm_skip_emulated_instruction(vcpu); + return __kvm_emulate_hypercall(vcpu, nr, a0, a1, a2, a3, op_64_bit, cpl, + complete_hypercall_exit); } EXPORT_SYMBOL_GPL(kvm_emulate_hypercall); diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index 6db13b696468..28adc8ea04bf 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -617,10 +617,12 @@ static inline bool user_exit_on_hypercall(struct kvm *kvm, unsigned long hc_nr) return kvm->arch.hypercall_exit_enabled & BIT(hc_nr); } -unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr, - unsigned long a0, unsigned long a1, - unsigned long a2, unsigned long a3, - int op_64_bit, int cpl); +int __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr, + unsigned long a0, unsigned long a1, + unsigned long a2, unsigned long a3, + int op_64_bit, int cpl, + int (*complete_hypercall)(struct kvm_vcpu *)); + int kvm_emulate_hypercall(struct kvm_vcpu *vcpu); #endif