linux-kernel - [PATCH 02/58] KVM: SVM: Allow direct guest access to PC debug port

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Message-Id: <11820734792649-git-send-email-avi@qumranet.com>
Date:	Sun, 17 Jun 2007 12:43:43 +0300
From:	Avi Kivity <avi@...ranet.com>
To:	kvm-devel@...ts.sourceforge.net
Cc:	linux-kernel@...r.kernel.org,
	Anthony Liguori <aliguori@...ibm.com>,
	Avi Kivity <avi@...ranet.com>
Subject: [PATCH 02/58] KVM: SVM: Allow direct guest access to PC debug port

From: Anthony Liguori <aliguori@...ibm.com>

The PC debug port is used for IO delay and does not require emulation.

Signed-off-by: Anthony Liguori <aliguori@...ibm.com>
Signed-off-by: Avi Kivity <avi@...ranet.com>
---
 drivers/kvm/svm.c |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index fa17d6d..6cd6a50 100644
--- a/drivers/kvm/svm.c
+++ b/drivers/kvm/svm.c
@@ -378,7 +378,7 @@ static __init int svm_hardware_setup(void)
 	int cpu;
 	struct page *iopm_pages;
 	struct page *msrpm_pages;
-	void *msrpm_va;
+	void *iopm_va, *msrpm_va;
 	int r;
 
 	kvm_emulator_want_group7_invlpg();
@@ -387,8 +387,10 @@ static __init int svm_hardware_setup(void)
 
 	if (!iopm_pages)
 		return -ENOMEM;
-	memset(page_address(iopm_pages), 0xff,
-					PAGE_SIZE * (1 << IOPM_ALLOC_ORDER));
+
+	iopm_va = page_address(iopm_pages);
+	memset(iopm_va, 0xff, PAGE_SIZE * (1 << IOPM_ALLOC_ORDER));
+	clear_bit(0x80, iopm_va); /* allow direct access to PC debug port */
 	iopm_base = page_to_pfn(iopm_pages) << PAGE_SHIFT;
 
 
-- 
1.5.0.6

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