From: Ingo Molnar <mingo@elte.hu>
To: Avi Kivity <avi@qumranet.com>
Cc: kvm-devel <kvm-devel@lists.sourceforge.net>,
linux-kernel@vger.kernel.org
Subject: [patch] KVM: always reload segment selectors
Date: Sun, 11 Mar 2007 13:52:33 +0100 [thread overview]
Message-ID: <20070311125233.GA17328@elte.hu> (raw)
In-Reply-To: <20070311124146.GA15115@elte.hu>
Subject: [patch] KVM: always reload segment selectors
From: Ingo Molnar <mingo@elte.hu>
failed VM entry on VMX might still change %fs or %gs, thus make sure
that KVM always reloads the segment selectors. This is crutial on both
x86 and x86_64: x86 has __KERNEL_PDA in %fs on which things like
'current' depends and x86_64 has 0 there and needs MSR_GS_BASE to work.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
drivers/kvm/vmx.c | 37 +++++++++++++++++++++----------------
1 file changed, 21 insertions(+), 16 deletions(-)
Index: linux/drivers/kvm/vmx.c
===================================================================
--- linux.orig/drivers/kvm/vmx.c
+++ linux/drivers/kvm/vmx.c
@@ -1896,6 +1896,27 @@ again:
[cr2]"i"(offsetof(struct kvm_vcpu, cr2))
: "cc", "memory" );
+ /*
+ * Reload segment selectors ASAP. (it's needed for a functional
+ * kernel: x86 relies on having __KERNEL_PDA in %fs and x86_64
+ * relies on having 0 in %gs for the CPU PDA to work.)
+ */
+ if (fs_gs_ldt_reload_needed) {
+ load_ldt(ldt_sel);
+ load_fs(fs_sel);
+ /*
+ * If we have to reload gs, we must take care to
+ * preserve our gs base.
+ */
+ local_irq_disable();
+ load_gs(gs_sel);
+#ifdef CONFIG_X86_64
+ wrmsrl(MSR_GS_BASE, vmcs_readl(HOST_GS_BASE));
+#endif
+ local_irq_enable();
+
+ reload_tss();
+ }
++kvm_stat.exits;
save_msrs(vcpu->guest_msrs, NR_BAD_MSRS);
@@ -1913,22 +1934,6 @@ again:
kvm_run->exit_reason = vmcs_read32(VM_INSTRUCTION_ERROR);
r = 0;
} else {
- if (fs_gs_ldt_reload_needed) {
- load_ldt(ldt_sel);
- load_fs(fs_sel);
- /*
- * If we have to reload gs, we must take care to
- * preserve our gs base.
- */
- local_irq_disable();
- load_gs(gs_sel);
-#ifdef CONFIG_X86_64
- wrmsrl(MSR_GS_BASE, vmcs_readl(HOST_GS_BASE));
-#endif
- local_irq_enable();
-
- reload_tss();
- }
/*
* Profile KVM exit RIPs:
*/
next parent reply other threads:[~2007-03-11 12:52 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20070311122441.GA10774@elte.hu>
[not found] ` <45F3F85D.7000509@qumranet.com>
[not found] ` <20070311124146.GA15115@elte.hu>
2007-03-11 12:52 ` Ingo Molnar [this message]
2007-03-11 13:04 ` [patch] KVM: always reload segment selectors Avi Kivity
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