From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f202.google.com (mail-pg1-f202.google.com [209.85.215.202]) (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 9CC9B3CD8A9 for ; Thu, 14 May 2026 21:05:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778792718; cv=none; b=a6XPtUftcMXWgAo/Vtb2KKTAObX/WMAZU9cxA+6ouYQxEUL/Tduy3fH9rocA4nN0h756l/S05UWQkRv4+isdAXoWEK6ZLBzynyq9VpDxcl4UJAsVBk4D5KrC6k+t9XF8kGK1Djk9tqaZ2eHh7jo8qze3eKw/qArvyL+UPW0EL5I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778792718; c=relaxed/simple; bh=Xktsb+EZGJ0O5wYa6cZIVh/oFRdhW/S6ru+cAqd520A=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=nbmmd0q+ZM/nmKXOChbhS1OEca4/sb6vic8lNcTpDWOHfJu2eWvJOvnx3yrehBNVXV7SppzCWu05un5srdkxjpfpx0WtC7hBjBw21a4pfhNry+0xPMq4aDRgshhTTgUH+247aseoru3cso0dF9iOqyX92f7r/daQCd3Jd9GFwyo= 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=RD6B+DdD; arc=none smtp.client-ip=209.85.215.202 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="RD6B+DdD" Received: by mail-pg1-f202.google.com with SMTP id 41be03b00d2f7-c828f0f5c23so2804874a12.1 for ; Thu, 14 May 2026 14:05:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1778792717; x=1779397517; 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=k0Quhz7quHfrJptiAjYdwWC6DonsOfYE619OS34mY4E=; b=RD6B+DdDgrNJeCpWpP7VYsQYEEeyhRk9ifZ/VlWHTlsBDTJOeV+4ikS/Of3VimYRCN 8DDL4naYHoGsfsNIqCweI8Hz984bC4XkHx9Yv1W30JtXypHJakPvtLPTdMGElHqd7quk TDsKV3jz6kKaBQhsZgRU/mAFGcTjnjYA5b35GMK1e2JM597N3sGGDGCVUPsaM6P2b9Pd 8I8cCLX4rbClD9ljqf9X7DaG8ilkLG6Fl4EsS2P0qo+9gB+jbZbrq2d2ovvgGH+iHVSL mRP/GE1fPnCJ8BABk4VcPg3GBEUFv5a8htuV0zcNkNgW7pRptVOG9oLFFDb2Mm8tSqq6 IlQA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1778792717; x=1779397517; 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=k0Quhz7quHfrJptiAjYdwWC6DonsOfYE619OS34mY4E=; b=r1o6N+mKEfj5IthotCmOGV8BO7vD4vXAq53TuLEnA3AbPUolIKkyCyOHQ9NF7N/F5g ioLEz/WEekNOXHJdq/HeAKh5G/mXH7XCa0i05Z7chHETlD6PJz+dWLdeqo9Ccmi4J+x3 qk+DirAK6x/cSIVCS8u/hyJwTrThJf8Z8WWxd6MGOlm9K6McK5dbe5wkoTpAfCD3ZOqn orxhJLcFGK8p1kr+SZKqnruU9FM+Zd0pVE9PAKC5JWBfmMyLZRFwRyFYXPp46o3rzqVB IsOBKAgPdZu66EuxVPcuUK65tXxLwr6Q0mCs49MaYVuR+QnaQBBpZ3piDuZEOavPMaPL ZqDQ== X-Gm-Message-State: AOJu0YzwpszLrhgsStJHXmVlr8lgq6jswAdJ87C/z7moaZcdMbLG7pNv a+n2crYWnLn2J51SVC3RIB23ZvDD7lryItuy0hKpFnK7JvQTULnSIr3AERJ2Qc+aevQ4KJ6WN3B Lq1gI0g== X-Received: from pfbg8.prod.google.com ([2002:a05:6a00:ae08:b0:83e:b5cc:11c3]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:3907:b0:82d:556b:7a01 with SMTP id d2e1a72fcca58-83f33c25b5bmr1206687b3a.16.1778792716654; Thu, 14 May 2026 14:05:16 -0700 (PDT) Reply-To: Sean Christopherson Date: Thu, 14 May 2026 14:04:52 -0700 In-Reply-To: <20260514210500.1626871-1-seanjc@google.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260514210500.1626871-1-seanjc@google.com> X-Mailer: git-send-email 2.54.0.563.g4f69b47b94-goog Message-ID: <20260514210500.1626871-13-seanjc@google.com> Subject: [kvm-unit-tests PATCH v3 12/20] x86/vmx: Communicate hypercalls via RAX, not a global field From: Sean Christopherson To: Paolo Bonzini Cc: kvm@vger.kernel.org, Sean Christopherson , Mathias Krause , Andrew Jones Content-Type: text/plain; charset="UTF-8" Communicate hypercall requests via RAX instead of a global field. To avoid false positives, use a larger magic value that is extremely unlikely to be resident in RAX at the time of VMCALL (avoiding false positives is is presumably why a global variable was used). Using RAX instead of a shared variable ensures multi-vCPU tests won't clobber each other's hypercalls (no such tests currently exist). Use the "abracadabra" magic number first introduced by KVM selftests, because if a dad joke is funny one time, it's funny every time. Signed-off-by: Sean Christopherson --- x86/vmx.c | 32 ++++++++++++++++++++------------ x86/vmx.h | 6 ------ 2 files changed, 20 insertions(+), 18 deletions(-) diff --git a/x86/vmx.c b/x86/vmx.c index 12e5d449..af7c4c20 100644 --- a/x86/vmx.c +++ b/x86/vmx.c @@ -59,7 +59,6 @@ static struct test_teardown_step teardown_steps[MAX_TEST_TEARDOWN_STEPS]; static test_guest_func v2_guest_main; -u64 hypercall_field; static int matched; static int guest_finished; @@ -1635,28 +1634,37 @@ static void test_vmx_caps(void) "MSR_IA32_VMX_EPT_VPID_CAP"); } +#define VMX_HYPERCALL_MAGIC 0xabacadabaULL + +#define HYPERCALL_MASK 0xFFF +#define HYPERCALL_VMEXIT 0x1 +#define HYPERCALL_VMABORT 0x2 +#define HYPERCALL_VMSKIP 0x3 + /* This function can only be called in guest */ void __attribute__((__used__)) hypercall(u32 hypercall_no) { - u64 val = 0; - val = (hypercall_no & HYPERCALL_MASK) | HYPERCALL_BIT; - hypercall_field = val; - asm volatile("vmcall\n\t"); + u64 val = (VMX_HYPERCALL_MAGIC << 12) | hypercall_no; + + asm volatile("vmcall\n\t" : "+a"(val)); } static bool is_hypercall(union exit_reason exit_reason) { + u64 hypercall_field = this_cpu_guest_regs()->rax; + return exit_reason.basic == VMX_VMCALL && - (hypercall_field & HYPERCALL_BIT); + (hypercall_field >> 12) == VMX_HYPERCALL_MAGIC; } static int handle_hypercall(void) { - ulong hypercall_no; + struct guest_regs *regs = this_cpu_guest_regs(); + u64 hypercall_field = regs->rax; - hypercall_no = hypercall_field & HYPERCALL_MASK; - hypercall_field = 0; - switch (hypercall_no) { + regs->rax = 0; + + switch (hypercall_field & HYPERCALL_MASK) { case HYPERCALL_VMEXIT: return VMX_TEST_VMEXIT; case HYPERCALL_VMABORT: @@ -1664,7 +1672,8 @@ static int handle_hypercall(void) case HYPERCALL_VMSKIP: return VMX_TEST_VMSKIP; default: - printf("ERROR : Invalid hypercall number : %ld\n", hypercall_no); + printf("ERROR : Invalid hypercall number : %ld\n", + hypercall_field & HYPERCALL_MASK); } return VMX_TEST_EXIT; } @@ -2060,7 +2069,6 @@ int main(int argc, const char *argv[]) int i = 0; setup_vm(); - hypercall_field = 0; /* We want xAPIC mode to test MMIO passthrough from L1 (us) to L2. */ smp_reset_apic(); diff --git a/x86/vmx.h b/x86/vmx.h index c1c6eba4..098a5ef4 100644 --- a/x86/vmx.h +++ b/x86/vmx.h @@ -588,12 +588,6 @@ enum vm_entry_failure_code { #define VMX_TEST_VMABORT 4 #define VMX_TEST_VMSKIP 5 -#define HYPERCALL_BIT (1ul << 12) -#define HYPERCALL_MASK 0xFFF -#define HYPERCALL_VMEXIT 0x1 -#define HYPERCALL_VMABORT 0x2 -#define HYPERCALL_VMSKIP 0x3 - #define EPTP_PG_WALK_LEN_SHIFT 3ul #define EPTP_PG_WALK_LEN_MASK 0x38ul #define EPTP_RESERV_BITS_MASK 0x1ful -- 2.54.0.563.g4f69b47b94-goog