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[PATCH v2 02/12] Add PV MSR to enable asynchronous page faults delivery.

 

 

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gleb at redhat

Nov 23, 2009, 6:05 AM

Post #1 of 2 (48 views)
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[PATCH v2 02/12] Add PV MSR to enable asynchronous page faults delivery.

Signed-off-by: Gleb Natapov <gleb [at] redhat>
---
arch/x86/include/asm/kvm_host.h | 3 ++
arch/x86/include/asm/kvm_para.h | 2 +
arch/x86/kvm/x86.c | 42 +++++++++++++++++++++++++++++++++++++-
include/linux/kvm.h | 1 +
4 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 06e0856..9598e85 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -374,6 +374,9 @@ struct kvm_vcpu_arch {
/* used for guest single stepping over the given code position */
u16 singlestep_cs;
unsigned long singlestep_rip;
+
+ u32 __user *apf_data;
+ u64 apf_msr_val;
};

struct kvm_mem_alias {
diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 5f580f2..222d5fd 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -15,9 +15,11 @@
#define KVM_FEATURE_CLOCKSOURCE 0
#define KVM_FEATURE_NOP_IO_DELAY 1
#define KVM_FEATURE_MMU_OP 2
+#define KVM_FEATURE_ASYNC_PF 3

#define MSR_KVM_WALL_CLOCK 0x11
#define MSR_KVM_SYSTEM_TIME 0x12
+#define MSR_KVM_ASYNC_PF_EN 0x13

#define KVM_MAX_MMU_OP_BATCH 32

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 35eea30..ce8e66d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -566,9 +566,9 @@ static inline u32 bit(int bitno)
* kvm-specific. Those are put in the beginning of the list.
*/

-#define KVM_SAVE_MSRS_BEGIN 2
+#define KVM_SAVE_MSRS_BEGIN 3
static u32 msrs_to_save[] = {
- MSR_KVM_SYSTEM_TIME, MSR_KVM_WALL_CLOCK,
+ MSR_KVM_SYSTEM_TIME, MSR_KVM_WALL_CLOCK, MSR_KVM_ASYNC_PF_EN,
MSR_IA32_SYSENTER_CS, MSR_IA32_SYSENTER_ESP, MSR_IA32_SYSENTER_EIP,
MSR_K6_STAR,
#ifdef CONFIG_X86_64
@@ -949,6 +949,26 @@ out:
return r;
}

+static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data)
+{
+ u64 gpa = data & ~0x3f;
+ int offset = offset_in_page(gpa);
+ unsigned long addr;
+
+ addr = gfn_to_hva(vcpu->kvm, gpa >> PAGE_SHIFT);
+ if (kvm_is_error_hva(addr))
+ return 1;
+
+ vcpu->arch.apf_data = (u32 __user*)(addr + offset);
+
+ /* check if address is mapped */
+ if (get_user(offset, vcpu->arch.apf_data)) {
+ vcpu->arch.apf_data = NULL;
+ return 1;
+ }
+ return 0;
+}
+
int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
{
switch (msr) {
@@ -1029,6 +1049,14 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
kvm_request_guest_time_update(vcpu);
break;
}
+ case MSR_KVM_ASYNC_PF_EN:
+ vcpu->arch.apf_msr_val = data;
+ if (data & 1) {
+ if (kvm_pv_enable_async_pf(vcpu, data))
+ return 1;
+ } else
+ vcpu->arch.apf_data = NULL;
+ break;
case MSR_IA32_MCG_CTL:
case MSR_IA32_MCG_STATUS:
case MSR_IA32_MC0_CTL ... MSR_IA32_MC0_CTL + 4 * KVM_MAX_MCE_BANKS - 1:
@@ -1221,6 +1249,9 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
case MSR_KVM_SYSTEM_TIME:
data = vcpu->arch.time;
break;
+ case MSR_KVM_ASYNC_PF_EN:
+ data = vcpu->arch.apf_msr_val;
+ break;
case MSR_IA32_P5_MC_ADDR:
case MSR_IA32_P5_MC_TYPE:
case MSR_IA32_MCG_CAP:
@@ -1343,6 +1374,7 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_XEN_HVM:
case KVM_CAP_ADJUST_CLOCK:
case KVM_CAP_VCPU_EVENTS:
+ case KVM_CAP_ASYNC_PF:
r = 1;
break;
case KVM_CAP_COALESCED_MMIO:
@@ -4965,6 +4997,9 @@ free_vcpu:

void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
{
+ vcpu->arch.apf_data = NULL;
+ vcpu->arch.apf_msr_val = 0;
+
vcpu_load(vcpu);
kvm_mmu_unload(vcpu);
vcpu_put(vcpu);
@@ -4982,6 +5017,9 @@ int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu)
vcpu->arch.dr6 = DR6_FIXED_1;
vcpu->arch.dr7 = DR7_FIXED_1;

+ vcpu->arch.apf_data = NULL;
+ vcpu->arch.apf_msr_val = 0;
+
return kvm_x86_ops->vcpu_reset(vcpu);
}

diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 92045a9..6af1c99 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -492,6 +492,7 @@ struct kvm_ioeventfd {
#ifdef __KVM_HAVE_VCPU_EVENTS
#define KVM_CAP_VCPU_EVENTS 41
#endif
+#define KVM_CAP_ASYNC_PF 42

#ifdef KVM_CAP_IRQ_ROUTING

--
1.6.5

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avi at redhat

Nov 25, 2009, 4:32 AM

Post #2 of 2 (44 views)
Permalink
Re: [PATCH v2 02/12] Add PV MSR to enable asynchronous page faults delivery. [In reply to]

On 11/23/2009 04:05 PM, Gleb Natapov wrote:
> Signed-off-by: Gleb Natapov<gleb [at] redhat>
> ---
> arch/x86/include/asm/kvm_host.h | 3 ++
> arch/x86/include/asm/kvm_para.h | 2 +
> arch/x86/kvm/x86.c | 42 +++++++++++++++++++++++++++++++++++++-
> include/linux/kvm.h | 1 +
> 4 files changed, 46 insertions(+), 2 deletions(-)
>
> #define MSR_KVM_WALL_CLOCK 0x11
> #define MSR_KVM_SYSTEM_TIME 0x12
> +#define MSR_KVM_ASYNC_PF_EN 0x13
>

Please use MSRs from the range 0x4b564dxx. The numbers below are
reserved by Intel (and in fact used by the old Pentiums).

Need documentation for the new MSR, say in Documentation/kvm/msr.txt.

> +static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data)
> +{
> + u64 gpa = data& ~0x3f;
> + int offset = offset_in_page(gpa);
> + unsigned long addr;
> +
> + addr = gfn_to_hva(vcpu->kvm, gpa>> PAGE_SHIFT);
> + if (kvm_is_error_hva(addr))
> + return 1;
> +
> + vcpu->arch.apf_data = (u32 __user*)(addr + offset);
> +
> + /* check if address is mapped */
> + if (get_user(offset, vcpu->arch.apf_data)) {
> + vcpu->arch.apf_data = NULL;
> + return 1;
> + }
>

What if the memory slot arrangement changes? This needs to be
revalidated (and gfn_to_hva() called again).

> + return 0;
> +}
> +
> int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
> {
> switch (msr) {
> @@ -1029,6 +1049,14 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
> kvm_request_guest_time_update(vcpu);
> break;
> }
> + case MSR_KVM_ASYNC_PF_EN:
> + vcpu->arch.apf_msr_val = data;
> + if (data& 1) {
> + if (kvm_pv_enable_async_pf(vcpu, data))
> + return 1;
>

Need to check before setting the msr value, so subsequent reads return
the old value.

> + } else
> + vcpu->arch.apf_data = NULL;
>

Need to check that bits 1:5 are zero. I think it's cleaner to move all
of the code to kvm_pv_enable_async_pf(), to have everything in one place.


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

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