linux-kernel - [PATCH] KVM: X86: Expose KVM_HINTS_REALTIME in KVM_GET_SUPPORTED

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Message-Id: <1603330475-7063-1-git-send-email-wanpengli@tencent.com>
Date:   Thu, 22 Oct 2020 09:34:35 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>
Subject: [PATCH] KVM: X86: Expose KVM_HINTS_REALTIME in KVM_GET_SUPPORTED_CPUID

From: Wanpeng Li <wanpengli@...cent.com>

Per KVM_GET_SUPPORTED_CPUID ioctl documentation:

This ioctl returns x86 cpuid features which are supported by both the 
hardware and kvm in its default configuration.

A well-behaved userspace should not set the bit if it is not supported.

Suggested-by: Jim Mattson <jmattson@...gle.com>
Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
---
 arch/x86/kvm/cpuid.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 06a278b..225d251 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -789,7 +789,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
 
 		entry->ebx = 0;
 		entry->ecx = 0;
-		entry->edx = 0;
+		entry->edx = (1 << KVM_HINTS_REALTIME);
 		break;
 	case 0x80000000:
 		entry->eax = min(entry->eax, 0x8000001f);
-- 
2.7.4