linux-kernel - [PATCH 1/2] x86/xen: don't indicate DCA support in pv domains

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Date:   Fri, 17 Feb 2017 08:36:24 +0100
From:   Juergen Gross <jgross@...e.com>
To:     linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
        x86@...nel.org
Cc:     boris.ostrovsky@...cle.com, hpa@...or.com, tglx@...utronix.de,
        mingo@...hat.com, Juergen Gross <jgross@...e.com>
Subject: [PATCH 1/2] x86/xen: don't indicate DCA support in pv domains

Xen doesn't support DCA (direct cache access) for pv domains. Clear
the corresponding capability indicator.

Signed-off-by: Juergen Gross <jgross@...e.com>
---
 arch/x86/xen/enlighten.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 51ef952..83399ce 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -461,6 +461,9 @@ static void __init xen_init_cpuid_mask(void)
 		cpuid_leaf1_ecx_mask &= ~xsave_mask; /* disable XSAVE & OSXSAVE */
 	if (xen_check_mwait())
 		cpuid_leaf1_ecx_set_mask = (1 << (X86_FEATURE_MWAIT % 32));
+
+	/* Disable DCA feature. */
+	setup_clear_cpu_cap(X86_FEATURE_DCA);
 }
 
 static void xen_set_debugreg(int reg, unsigned long val)
-- 
2.10.2