linux-kernel - Re: [PATCH] KVM-Use value reading from MSR when construct the eptp in VMX mode

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Message-ID: <CA+U0gVif67d_GAAwac=dX6U_EBdw187yXgXwERaqnbWvM6mNSg@mail.gmail.com>
Date:	Mon, 25 Aug 2014 11:21:40 +0800
From:	Dennis Chen <kernel.org.gnu@...il.com>
To:	Wanpeng Li <wanpeng.li@...ux.intel.com>
Cc:	kvm <kvm@...r.kernel.org>, linux-kernel@...r.kernel.org,
	pbonzini@...hat.com, gleb@...nel.org,
	Avi Kivity <avi.kivity@...il.com>
Subject: Re: [PATCH] KVM-Use value reading from MSR when construct the eptp in
 VMX mode

On Mon, Aug 25, 2014 at 7:14 AM, Wanpeng Li <wanpeng.li@...ux.intel.com> wrote:
> Please Cc kvm ml.

You've done that for me, thanks. The page-walk length sanity check has
been done in the hardware_setup() function, so it's not necessary in
this patch, but I still think it does make sense for the memory type
check, any comments, guys?

> On Sun, Aug 24, 2014 at 11:54:32AM +0800, Dennis Chen wrote:
>>This patch is used to construct the eptp in vmx mode with values
>>readed from MSR according to the intel x86 software developer's
>>manual.
>>
>>Signed-off-by: Dennis Chen <kernel.org.gnu@...il.com>
>>---
>> arch/x86/include/asm/vmx.h |    1 +
>> arch/x86/kvm/vmx.c         |   21 +++++++++++++++++----
>> 2 files changed, 18 insertions(+), 4 deletions(-)
>>
>>diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
>>index bcbfade..bf82a77 100644
>>--- a/arch/x86/include/asm/vmx.h
>>+++ b/arch/x86/include/asm/vmx.h
>>@@ -417,6 +417,7 @@ enum vmcs_field {
>> #define VMX_EPT_GAW_EPTP_SHIFT            3
>> #define VMX_EPT_AD_ENABLE_BIT            (1ull << 6)
>> #define VMX_EPT_DEFAULT_MT            0x6ull
>>+#define VMX_EPT_UC_MT                0x0ull
>> #define VMX_EPT_READABLE_MASK            0x1ull
>> #define VMX_EPT_WRITABLE_MASK            0x2ull
>> #define VMX_EPT_EXECUTABLE_MASK            0x4ull
>>diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>>index bfe11cf..7add5ce 100644
>>--- a/arch/x86/kvm/vmx.c
>>+++ b/arch/x86/kvm/vmx.c
>>@@ -3477,11 +3477,24 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu,
>>unsigned long cr0)
>>
>> static u64 construct_eptp(unsigned long root_hpa)
>> {
>>-    u64 eptp;
>>+    u64 eptp, pwl;
>>+
>>+    if (cpu_has_vmx_ept_4levels())
>>+        pwl = VMX_EPT_DEFAULT_GAW << VMX_EPT_GAW_EPTP_SHIFT;
>>+    else {
>>+        WARN(1, "Unsupported page-walk length of 4.\n");
>>+        BUG();
>>+    }
>>+
>>+    if (cpu_has_vmx_eptp_writeback())
>>+        eptp = VMX_EPT_DEFAULT_MT | pwl;
>>+    else if (cpu_has_vmx_eptp_uncacheable())
>>+        eptp = VMX_EPT_UC_MT | pwl;
>>+    else {
>>+        WARN(1, "Unsupported memory type config in vmx eptp.\n");
>>+        BUG();
>>+    }
>>
>>-    /* TODO write the value reading from MSR */
>>-    eptp = VMX_EPT_DEFAULT_MT |
>>-        VMX_EPT_DEFAULT_GAW << VMX_EPT_GAW_EPTP_SHIFT;
>>     if (enable_ept_ad_bits)
>>         eptp |= VMX_EPT_AD_ENABLE_BIT;
>>     eptp |= (root_hpa & PAGE_MASK);
>>--
>>1.7.9.5
--
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