[PATCH] x86: use kvm_read/write_guest_virt for reading and writing segment descriptors

[PATCH] x86: use kvm_read/write_guest_virt for reading and writing segment descriptors

[Mikhail Ershov]

Descriptor table can be placed on two non-contiguous pages.
It is better to read descriptor by linear address.

Signed-off-by: Mikhail Ershov <Mike.Ershov@gmail.com>
---
 arch/x86/kvm/x86.c |   10 ++--------
 1 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 850cf56..13f39bb 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4017,7 +4017,6 @@ static void get_segment_descriptor_dtable(struct
kvm_vcpu *vcpu,
 static int load_guest_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
                     struct desc_struct *seg_desc)
 {
-   gpa_t gpa;
    struct descriptor_table dtable;
    u16 index = selector >> 3;

@@ -4027,16 +4026,13 @@ static int
load_guest_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
        kvm_queue_exception_e(vcpu, GP_VECTOR, selector & 0xfffc);
        return 1;
    }
-   gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, dtable.base);
-   gpa += index * 8;
-   return kvm_read_guest(vcpu->kvm, gpa, seg_desc, 8);
+   return kvm_read_guest_virt(dtable.base + index*8, seg_desc,
sizeof(*seg_desc), vcpu);
 }

 /* allowed just for 8 bytes segments */
 static int save_guest_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
                     struct desc_struct *seg_desc)
 {
-   gpa_t gpa;
    struct descriptor_table dtable;
    u16 index = selector >> 3;

@@ -4044,9 +4040,7 @@ static int save_guest_segment_descriptor(struct
kvm_vcpu *vcpu, u16 selector,

    if (dtable.limit < index * 8 + 7)
        return 1;
-   gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, dtable.base);
-   gpa += index * 8;
-   return kvm_write_guest(vcpu->kvm, gpa, seg_desc, 8);
+   return kvm_write_guest_virt(dtable.base + index*8, seg_desc,
sizeof(*seg_desc), vcpu);
 }

 static u32 get_tss_base_addr(struct kvm_vcpu *vcpu,
-- 
1.6.0.4

Re: [PATCH] x86: use kvm_read/write_guest_virt for reading and writing segment descriptors

[Avi Kivity]

On 08/10/2009 08:11 PM, Mikhail Ershov wrote:
> Descriptor table can be placed on two non-contiguous pages.
> It is better to read descriptor by linear address.
>    

Patch is good, but is whitespace-corrupted.  Please send as an 
attachment (or using git-send-email).

Make sure the attachment is plain/text so mail clients can display it 
inline.

-- 
error compiling committee.c: too many arguments to function

Re: [PATCH] x86: use kvm_read/write_guest_virt for reading and writing segment descriptors

[Mikhail Ershov]

[-- Attachment #1: Type: text/plain, Size: 560 bytes --]

The patch is in attachment.

2009/8/16 Avi Kivity <avi@redhat.com>:
> On 08/10/2009 08:11 PM, Mikhail Ershov wrote:
>>
>> Descriptor table can be placed on two non-contiguous pages.
>> It is better to read descriptor by linear address.
>>
>
> Patch is good, but is whitespace-corrupted.  Please send as an attachment
> (or using git-send-email).
>
> Make sure the attachment is plain/text so mail clients can display it
> inline.
>
> --
> error compiling committee.c: too many arguments to function
>
>

-- 
Best regards,
Mikhail Ershov

[-- Attachment #2: descriptors-read-write.patch.txt --]
[-- Type: text/plain, Size: 2023 bytes --]

From eb73019762ec299ded618d807f5c14859491adbc Mon Sep 17 00:00:00 2001
From: Mikhail Ershov <Mike.Ershov@gmail.com>
Date: Wed, 19 Aug 2009 14:08:07 +0400
Subject: [PATCH] Using kvm_read/write_guest_virt to read and write segment descriptors.

 Segment descriptors tables can be placed on two non-contiguous pages.
This patch makes reading segment descriptors by linear address.

Signed-off-by: Mikhail Ershov <Mike.Ershov@gmail.com>
---
 arch/x86/kvm/x86.c |   10 ++--------
 1 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 52d5d72..aa2dd12 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4017,7 +4017,6 @@ static void get_segment_descriptor_dtable(struct kvm_vcpu *vcpu,
 static int load_guest_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
 					 struct desc_struct *seg_desc)
 {
-	gpa_t gpa;
 	struct descriptor_table dtable;
 	u16 index = selector >> 3;
 
@@ -4027,16 +4026,13 @@ static int load_guest_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
 		kvm_queue_exception_e(vcpu, GP_VECTOR, selector & 0xfffc);
 		return 1;
 	}
-	gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, dtable.base);
-	gpa += index * 8;
-	return kvm_read_guest(vcpu->kvm, gpa, seg_desc, 8);
+	return kvm_read_guest_virt(dtable.base + index*8, seg_desc, sizeof(*seg_desc), vcpu);
 }
 
 /* allowed just for 8 bytes segments */
 static int save_guest_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
 					 struct desc_struct *seg_desc)
 {
-	gpa_t gpa;
 	struct descriptor_table dtable;
 	u16 index = selector >> 3;
 
@@ -4044,9 +4040,7 @@ static int save_guest_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
 
 	if (dtable.limit < index * 8 + 7)
 		return 1;
-	gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, dtable.base);
-	gpa += index * 8;
-	return kvm_write_guest(vcpu->kvm, gpa, seg_desc, 8);
+	return kvm_write_guest_virt(dtable.base + index*8, seg_desc, sizeof(*seg_desc), vcpu);
 }
 
 static u32 get_tss_base_addr(struct kvm_vcpu *vcpu,
-- 
1.6.0.4

Re: [PATCH] x86: use kvm_read/write_guest_virt for reading and writing segment descriptors

[Avi Kivity]

On 08/19/2009 01:42 PM, Mikhail Ershov wrote:
> The patch is in attachment.
>
>    

Applied, thanks.

-- 
error compiling committee.c: too many arguments to function