* [PATCH v2] kvm: vmx: Stop wasting a page for guest_msrs
@ 2019-12-04 0:24 Jim Mattson
2019-12-04 9:31 ` Paolo Bonzini
0 siblings, 1 reply; 2+ messages in thread
From: Jim Mattson @ 2019-12-04 0:24 UTC (permalink / raw)
To: kvm, Sean Christopherson, Paolo Bonzini; +Cc: Jim Mattson, Liran Alon
We will never need more guest_msrs than there are indices in
vmx_msr_index. Thus, at present, the guest_msrs array will not exceed
168 bytes.
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Liran Alon <liran.alon@oracle.com>
---
v1 -> v2:
Changed NR_GUEST_MSRS to NR_SHARED_MSRS.
Added BUILD_BUG_ON(ARRAY_SIZE(vmx_msr_index) != NR_SHARED_MSRS).
arch/x86/kvm/vmx/vmx.c | 12 ++----------
arch/x86/kvm/vmx/vmx.h | 8 +++++++-
2 files changed, 9 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 1b9ab4166397d..e3394c839dea6 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6666,7 +6666,6 @@ static void vmx_free_vcpu(struct kvm_vcpu *vcpu)
free_vpid(vmx->vpid);
nested_vmx_free_vcpu(vcpu);
free_loaded_vmcs(vmx->loaded_vmcs);
- kfree(vmx->guest_msrs);
kvm_vcpu_uninit(vcpu);
kmem_cache_free(x86_fpu_cache, vmx->vcpu.arch.user_fpu);
kmem_cache_free(x86_fpu_cache, vmx->vcpu.arch.guest_fpu);
@@ -6723,12 +6722,7 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
goto uninit_vcpu;
}
- vmx->guest_msrs = kmalloc(PAGE_SIZE, GFP_KERNEL_ACCOUNT);
- BUILD_BUG_ON(ARRAY_SIZE(vmx_msr_index) * sizeof(vmx->guest_msrs[0])
- > PAGE_SIZE);
-
- if (!vmx->guest_msrs)
- goto free_pml;
+ BUILD_BUG_ON(ARRAY_SIZE(vmx_msr_index) != NR_SHARED_MSRS);
for (i = 0; i < ARRAY_SIZE(vmx_msr_index); ++i) {
u32 index = vmx_msr_index[i];
@@ -6760,7 +6754,7 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
err = alloc_loaded_vmcs(&vmx->vmcs01);
if (err < 0)
- goto free_msrs;
+ goto free_pml;
msr_bitmap = vmx->vmcs01.msr_bitmap;
vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_TSC, MSR_TYPE_R);
@@ -6822,8 +6816,6 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
free_vmcs:
free_loaded_vmcs(vmx->loaded_vmcs);
-free_msrs:
- kfree(vmx->guest_msrs);
free_pml:
vmx_destroy_pml_buffer(vmx);
uninit_vcpu:
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 7c1b978b2df44..a4f7f737c5d44 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -22,6 +22,12 @@ extern u32 get_umwait_control_msr(void);
#define X2APIC_MSR(r) (APIC_BASE_MSR + ((r) >> 4))
+#ifdef CONFIG_X86_64
+#define NR_SHARED_MSRS 7
+#else
+#define NR_SHARED_MSRS 4
+#endif
+
#define NR_LOADSTORE_MSRS 8
struct vmx_msrs {
@@ -206,7 +212,7 @@ struct vcpu_vmx {
u32 idt_vectoring_info;
ulong rflags;
- struct shared_msr_entry *guest_msrs;
+ struct shared_msr_entry guest_msrs[NR_SHARED_MSRS];
int nmsrs;
int save_nmsrs;
bool guest_msrs_ready;
--
2.24.0.393.g34dc348eaf-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] kvm: vmx: Stop wasting a page for guest_msrs
2019-12-04 0:24 [PATCH v2] kvm: vmx: Stop wasting a page for guest_msrs Jim Mattson
@ 2019-12-04 9:31 ` Paolo Bonzini
0 siblings, 0 replies; 2+ messages in thread
From: Paolo Bonzini @ 2019-12-04 9:31 UTC (permalink / raw)
To: Jim Mattson, kvm, Sean Christopherson; +Cc: Liran Alon
On 04/12/19 01:24, Jim Mattson wrote:
> We will never need more guest_msrs than there are indices in
> vmx_msr_index. Thus, at present, the guest_msrs array will not exceed
> 168 bytes.
>
> Signed-off-by: Jim Mattson <jmattson@google.com>
> Reviewed-by: Liran Alon <liran.alon@oracle.com>
> ---
> v1 -> v2:
> Changed NR_GUEST_MSRS to NR_SHARED_MSRS.
> Added BUILD_BUG_ON(ARRAY_SIZE(vmx_msr_index) != NR_SHARED_MSRS).
>
> arch/x86/kvm/vmx/vmx.c | 12 ++----------
> arch/x86/kvm/vmx/vmx.h | 8 +++++++-
> 2 files changed, 9 insertions(+), 11 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 1b9ab4166397d..e3394c839dea6 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6666,7 +6666,6 @@ static void vmx_free_vcpu(struct kvm_vcpu *vcpu)
> free_vpid(vmx->vpid);
> nested_vmx_free_vcpu(vcpu);
> free_loaded_vmcs(vmx->loaded_vmcs);
> - kfree(vmx->guest_msrs);
> kvm_vcpu_uninit(vcpu);
> kmem_cache_free(x86_fpu_cache, vmx->vcpu.arch.user_fpu);
> kmem_cache_free(x86_fpu_cache, vmx->vcpu.arch.guest_fpu);
> @@ -6723,12 +6722,7 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
> goto uninit_vcpu;
> }
>
> - vmx->guest_msrs = kmalloc(PAGE_SIZE, GFP_KERNEL_ACCOUNT);
> - BUILD_BUG_ON(ARRAY_SIZE(vmx_msr_index) * sizeof(vmx->guest_msrs[0])
> - > PAGE_SIZE);
> -
> - if (!vmx->guest_msrs)
> - goto free_pml;
> + BUILD_BUG_ON(ARRAY_SIZE(vmx_msr_index) != NR_SHARED_MSRS);
>
> for (i = 0; i < ARRAY_SIZE(vmx_msr_index); ++i) {
> u32 index = vmx_msr_index[i];
> @@ -6760,7 +6754,7 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
>
> err = alloc_loaded_vmcs(&vmx->vmcs01);
> if (err < 0)
> - goto free_msrs;
> + goto free_pml;
>
> msr_bitmap = vmx->vmcs01.msr_bitmap;
> vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_TSC, MSR_TYPE_R);
> @@ -6822,8 +6816,6 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
>
> free_vmcs:
> free_loaded_vmcs(vmx->loaded_vmcs);
> -free_msrs:
> - kfree(vmx->guest_msrs);
> free_pml:
> vmx_destroy_pml_buffer(vmx);
> uninit_vcpu:
> diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
> index 7c1b978b2df44..a4f7f737c5d44 100644
> --- a/arch/x86/kvm/vmx/vmx.h
> +++ b/arch/x86/kvm/vmx/vmx.h
> @@ -22,6 +22,12 @@ extern u32 get_umwait_control_msr(void);
>
> #define X2APIC_MSR(r) (APIC_BASE_MSR + ((r) >> 4))
>
> +#ifdef CONFIG_X86_64
> +#define NR_SHARED_MSRS 7
> +#else
> +#define NR_SHARED_MSRS 4
> +#endif
> +
> #define NR_LOADSTORE_MSRS 8
>
> struct vmx_msrs {
> @@ -206,7 +212,7 @@ struct vcpu_vmx {
> u32 idt_vectoring_info;
> ulong rflags;
>
> - struct shared_msr_entry *guest_msrs;
> + struct shared_msr_entry guest_msrs[NR_SHARED_MSRS];
> int nmsrs;
> int save_nmsrs;
> bool guest_msrs_ready;
>
Queued, thanks.
Paolo
^ permalink raw reply [flat|nested] 2+ messages in thread
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2019-12-04 0:24 [PATCH v2] kvm: vmx: Stop wasting a page for guest_msrs Jim Mattson
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