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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v5 rebased 3/4] nested vmx: optimize for bulk access of virtual VMCS
Acked-by Eddie Dong <eddie.dong@xxxxxxxxx>
> -----Original Message-----
> From: Xu, Dongxiao
> Sent: Wednesday, January 23, 2013 10:32 PM
> To: xen-devel@xxxxxxxxxxxxxxxxxxx
> Cc: Dong, Eddie; Nakajima, Jun; Zhang, Xiantao; JBeulich@xxxxxxxx
> Subject: [PATCH v5 rebased 3/4] nested vmx: optimize for bulk access of
> virtual VMCS
>
> After we use the VMREAD/VMWRITE to build up the virtual VMCS, each
> access to the virtual VMCS needs two VMPTRLD and one VMCLEAR to
> switch the environment, which might be an overhead to performance.
> This commit tries to handle multiple virtual VMCS access together
> to improve the performance.
>
> Signed-off-by: Dongxiao Xu <dongxiao.xu@xxxxxxxxx>
> ---
> xen/arch/x86/hvm/vmx/vmcs.c | 10 +++
> xen/arch/x86/hvm/vmx/vvmx.c | 126
> +++++++++++++++++++++++++++++++-----
> xen/include/asm-x86/hvm/vmx/vvmx.h | 2 +
> 3 files changed, 122 insertions(+), 16 deletions(-)
>
> diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
> index 82a8d91..f89ea93 100644
> --- a/xen/arch/x86/hvm/vmx/vmcs.c
> +++ b/xen/arch/x86/hvm/vmx/vmcs.c
> @@ -31,6 +31,7 @@
> #include <asm/hvm/io.h>
> #include <asm/hvm/support.h>
> #include <asm/hvm/vmx/vmx.h>
> +#include <asm/hvm/vmx/vvmx.h>
> #include <asm/hvm/vmx/vmcs.h>
> #include <asm/flushtlb.h>
> #include <xen/event.h>
> @@ -423,6 +424,13 @@ static void vmx_load_vmcs(struct vcpu *v)
>
> int vmx_cpu_up_prepare(unsigned int cpu)
> {
> + /*
> + * If nvmx_cpu_up_prepare() failed, do not return failure and just
> fallback
> + * to legacy mode for vvmcs synchronization.
> + */
> + if ( nvmx_cpu_up_prepare(cpu) != 0 )
> + printk("CPU%d: Could not allocate virtual VMCS buffer.\n", cpu);
> +
> if ( per_cpu(vmxon_region, cpu) != NULL )
> return 0;
>
> @@ -431,6 +439,7 @@ int vmx_cpu_up_prepare(unsigned int cpu)
> return 0;
>
> printk("CPU%d: Could not allocate host VMCS\n", cpu);
> + nvmx_cpu_dead(cpu);
> return -ENOMEM;
> }
>
> @@ -438,6 +447,7 @@ void vmx_cpu_dead(unsigned int cpu)
> {
> vmx_free_vmcs(per_cpu(vmxon_region, cpu));
> per_cpu(vmxon_region, cpu) = NULL;
> + nvmx_cpu_dead(cpu);
> }
>
> int vmx_cpu_up(void)
> diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c
> index 8000f84..1e1ad56 100644
> --- a/xen/arch/x86/hvm/vmx/vvmx.c
> +++ b/xen/arch/x86/hvm/vmx/vvmx.c
> @@ -28,8 +28,31 @@
> #include <asm/hvm/vmx/vvmx.h>
> #include <asm/hvm/nestedhvm.h>
>
> +static DEFINE_PER_CPU(u64 *, vvmcs_buf);
> +
> static void nvmx_purge_vvmcs(struct vcpu *v);
>
> +#define VMCS_BUF_SIZE 100
> +
> +int nvmx_cpu_up_prepare(unsigned int cpu)
> +{
> + if ( per_cpu(vvmcs_buf, cpu) != NULL )
> + return 0;
> +
> + per_cpu(vvmcs_buf, cpu) = xzalloc_array(u64, VMCS_BUF_SIZE);
> +
> + if ( per_cpu(vvmcs_buf, cpu) != NULL )
> + return 0;
> +
> + return -ENOMEM;
> +}
> +
> +void nvmx_cpu_dead(unsigned int cpu)
> +{
> + xfree(per_cpu(vvmcs_buf, cpu));
> + per_cpu(vvmcs_buf, cpu) = NULL;
> +}
> +
> int nvmx_vcpu_initialise(struct vcpu *v)
> {
> struct nestedvmx *nvmx = &vcpu_2_nvmx(v);
> @@ -834,6 +857,40 @@ static void vvmcs_to_shadow(void *vvmcs, unsigned
> int field)
> __vmwrite(field, value);
> }
>
> +static void vvmcs_to_shadow_bulk(struct vcpu *v, unsigned int n,
> + const u16 *field)
> +{
> + struct nestedvcpu *nvcpu = &vcpu_nestedhvm(v);
> + void *vvmcs = nvcpu->nv_vvmcx;
> + u64 *value = this_cpu(vvmcs_buf);
> + unsigned int i;
> +
> + if ( !cpu_has_vmx_vmcs_shadowing )
> + goto fallback;
> +
> + if ( !value || n > VMCS_BUF_SIZE )
> + {
> + gdprintk(XENLOG_DEBUG, "vmcs sync fall back to non-bulk mode,
> \
> + buffer: %p, buffer size: %d, fields number: %d.\n",
> + value, VMCS_BUF_SIZE, n);
> + goto fallback;
> + }
> +
> + virtual_vmcs_enter(vvmcs);
> + for ( i = 0; i < n; i++ )
> + value[i] = __vmread(field[i]);
> + virtual_vmcs_exit(vvmcs);
> +
> + for ( i = 0; i < n; i++ )
> + __vmwrite(field[i], value[i]);
> +
> + return;
> +
> +fallback:
> + for ( i = 0; i < n; i++ )
> + vvmcs_to_shadow(vvmcs, field[i]);
> +}
> +
> static void shadow_to_vvmcs(void *vvmcs, unsigned int field)
> {
> u64 value;
> @@ -844,6 +901,40 @@ static void shadow_to_vvmcs(void *vvmcs, unsigned
> int field)
> __set_vvmcs(vvmcs, field, value);
> }
>
> +static void shadow_to_vvmcs_bulk(struct vcpu *v, unsigned int n,
> + const u16 *field)
> +{
> + struct nestedvcpu *nvcpu = &vcpu_nestedhvm(v);
> + void *vvmcs = nvcpu->nv_vvmcx;
> + u64 *value = this_cpu(vvmcs_buf);
> + unsigned int i;
> +
> + if ( !cpu_has_vmx_vmcs_shadowing )
> + goto fallback;
> +
> + if ( !value || n > VMCS_BUF_SIZE )
> + {
> + gdprintk(XENLOG_DEBUG, "vmcs sync fall back to non-bulk mode,
> \
> + buffer: %p, buffer size: %d, fields number: %d.\n",
> + value, VMCS_BUF_SIZE, n);
> + goto fallback;
> + }
> +
> + for ( i = 0; i < n; i++ )
> + value[i] = __vmread(field[i]);
> +
> + virtual_vmcs_enter(vvmcs);
> + for ( i = 0; i < n; i++ )
> + __vmwrite(field[i], value[i]);
> + virtual_vmcs_exit(vvmcs);
> +
> + return;
> +
> +fallback:
> + for ( i = 0; i < n; i++ )
> + shadow_to_vvmcs(vvmcs, field[i]);
> +}
> +
> static void load_shadow_control(struct vcpu *v)
> {
> /*
> @@ -867,13 +958,18 @@ static void load_shadow_guest_state(struct vcpu
> *v)
> {
> struct nestedvcpu *nvcpu = &vcpu_nestedhvm(v);
> void *vvmcs = nvcpu->nv_vvmcx;
> - int i;
> u32 control;
> u64 cr_gh_mask, cr_read_shadow;
>
> + static const u16 vmentry_fields[] = {
> + VM_ENTRY_INTR_INFO,
> + VM_ENTRY_EXCEPTION_ERROR_CODE,
> + VM_ENTRY_INSTRUCTION_LEN,
> + };
> +
> /* vvmcs.gstate to shadow vmcs.gstate */
> - for ( i = 0; i < ARRAY_SIZE(vmcs_gstate_field); i++ )
> - vvmcs_to_shadow(vvmcs, vmcs_gstate_field[i]);
> + vvmcs_to_shadow_bulk(v, ARRAY_SIZE(vmcs_gstate_field),
> + vmcs_gstate_field);
>
> hvm_set_cr0(__get_vvmcs(vvmcs, GUEST_CR0));
> hvm_set_cr4(__get_vvmcs(vvmcs, GUEST_CR4));
> @@ -887,9 +983,7 @@ static void load_shadow_guest_state(struct vcpu *v)
>
> hvm_funcs.set_tsc_offset(v, v->arch.hvm_vcpu.cache_tsc_offset);
>
> - vvmcs_to_shadow(vvmcs, VM_ENTRY_INTR_INFO);
> - vvmcs_to_shadow(vvmcs, VM_ENTRY_EXCEPTION_ERROR_CODE);
> - vvmcs_to_shadow(vvmcs, VM_ENTRY_INSTRUCTION_LEN);
> + vvmcs_to_shadow_bulk(v, ARRAY_SIZE(vmentry_fields),
> vmentry_fields);
>
> /*
> * While emulate CR0 and CR4 for nested virtualization, set the
> CR0/CR4
> @@ -909,10 +1003,13 @@ static void load_shadow_guest_state(struct vcpu
> *v)
> if ( nvmx_ept_enabled(v) && hvm_pae_enabled(v) &&
> (v->arch.hvm_vcpu.guest_efer & EFER_LMA) )
> {
> - vvmcs_to_shadow(vvmcs, GUEST_PDPTR0);
> - vvmcs_to_shadow(vvmcs, GUEST_PDPTR1);
> - vvmcs_to_shadow(vvmcs, GUEST_PDPTR2);
> - vvmcs_to_shadow(vvmcs, GUEST_PDPTR3);
> + static const u16 gpdptr_fields[] = {
> + GUEST_PDPTR0,
> + GUEST_PDPTR1,
> + GUEST_PDPTR2,
> + GUEST_PDPTR3,
> + };
> + vvmcs_to_shadow_bulk(v, ARRAY_SIZE(gpdptr_fields),
> gpdptr_fields);
> }
>
> /* TODO: CR3 target control */
> @@ -1003,13 +1100,12 @@ static void virtual_vmentry(struct cpu_user_regs
> *regs)
>
> static void sync_vvmcs_guest_state(struct vcpu *v, struct cpu_user_regs
> *regs)
> {
> - int i;
> struct nestedvcpu *nvcpu = &vcpu_nestedhvm(v);
> void *vvmcs = nvcpu->nv_vvmcx;
>
> /* copy shadow vmcs.gstate back to vvmcs.gstate */
> - for ( i = 0; i < ARRAY_SIZE(vmcs_gstate_field); i++ )
> - shadow_to_vvmcs(vvmcs, vmcs_gstate_field[i]);
> + shadow_to_vvmcs_bulk(v, ARRAY_SIZE(vmcs_gstate_field),
> + vmcs_gstate_field);
> /* RIP, RSP are in user regs */
> __set_vvmcs(vvmcs, GUEST_RIP, regs->eip);
> __set_vvmcs(vvmcs, GUEST_RSP, regs->esp);
> @@ -1021,13 +1117,11 @@ static void sync_vvmcs_guest_state(struct vcpu
> *v, struct cpu_user_regs *regs)
>
> static void sync_vvmcs_ro(struct vcpu *v)
> {
> - int i;
> struct nestedvcpu *nvcpu = &vcpu_nestedhvm(v);
> struct nestedvmx *nvmx = &vcpu_2_nvmx(v);
> void *vvmcs = nvcpu->nv_vvmcx;
>
> - for ( i = 0; i < ARRAY_SIZE(vmcs_ro_field); i++ )
> - shadow_to_vvmcs(nvcpu->nv_vvmcx, vmcs_ro_field[i]);
> + shadow_to_vvmcs_bulk(v, ARRAY_SIZE(vmcs_ro_field), vmcs_ro_field);
>
> /* Adjust exit_reason/exit_qualifciation for violation case */
> if ( __get_vvmcs(vvmcs, VM_EXIT_REASON) ==
> EXIT_REASON_EPT_VIOLATION )
> diff --git a/xen/include/asm-x86/hvm/vmx/vvmx.h
> b/xen/include/asm-x86/hvm/vmx/vvmx.h
> index 73a67cc..3874525 100644
> --- a/xen/include/asm-x86/hvm/vmx/vvmx.h
> +++ b/xen/include/asm-x86/hvm/vmx/vvmx.h
> @@ -229,5 +229,7 @@ int nept_translate_l2ga(struct vcpu *v, paddr_t l2ga,
> unsigned int *page_order, uint32_t rwx_acc,
> unsigned long *l1gfn, uint8_t *p2m_acc,
> uint64_t *exit_qual, uint32_t *exit_reason);
> +int nvmx_cpu_up_prepare(unsigned int cpu);
> +void nvmx_cpu_dead(unsigned int cpu);
> #endif /* __ASM_X86_HVM_VVMX_H__ */
>
> --
> 1.7.1
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