On 4/29/07, He, Qing <[EMAIL PROTECTED]> wrote:
> This patch enables IO bitmaps control on vmx and unmask the 0x80 port to
> avoid VMEXITs caused by accessing port 0x80. 0x80 is used as delays (see
> include/asm/io.h), and handling VMEXITs on its access is unnecessary but
> slows things down. This patch improves kernel build test at around
> 3%~5%.
> Because every VM uses the same io bitmap, it is shared between
> all VMs rather than a per-VM data structure.
>
> Signed-off-by: Qing He <[EMAIL PROTECTED]>
>
>
> diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
> index 1d2b41b..a91d71f 100644
> --- a/drivers/kvm/vmx.c
> +++ b/drivers/kvm/vmx.c
> @@ -33,6 +33,8 @@ MODULE_LICENSE("GPL");
> static DEFINE_PER_CPU(struct vmcs *, vmxarea);
> static DEFINE_PER_CPU(struct vmcs *, current_vmcs);
>
> +static char *vmx_io_bitmap;
> +
> #ifdef CONFIG_X86_64
> #define HOST_IS_64 1
> #else
> @@ -1127,8 +1129,8 @@ static int vmx_vcpu_setup(struct kvm_vcpu *vcpu)
> vmcs_write32(GUEST_PENDING_DBG_EXCEPTIONS, 0);
>
> /* I/O */
> - vmcs_write64(IO_BITMAP_A, 0);
> - vmcs_write64(IO_BITMAP_B, 0);
> + vmcs_write64(IO_BITMAP_A, (unsigned long) __pa(vmx_io_bitmap));
> + vmcs_write64(IO_BITMAP_B, (unsigned long) __pa(vmx_io_bitmap +
> PAGE_SIZE));
>
> guest_write_tsc(0);
>
> @@ -1148,7 +1150,7 @@ static int vmx_vcpu_setup(struct kvm_vcpu *vcpu)
> CPU_BASED_HLT_EXITING /* 20.6.2
> */
> | CPU_BASED_CR8_LOAD_EXITING /* 20.6.2
> */
> | CPU_BASED_CR8_STORE_EXITING /* 20.6.2
> */
> - | CPU_BASED_UNCOND_IO_EXITING /* 20.6.2
> */
> + | CPU_BASED_ACTIVATE_IO_BITMAP /* 20.6.2
> */
> | CPU_BASED_MOV_DR_EXITING
> | CPU_BASED_USE_TSC_OFFSETING /* 21.3
> */
> );
> @@ -2190,11 +2192,39 @@ static struct kvm_arch_ops vmx_arch_ops = {
>
> static int __init vmx_init(void)
> {
> - return kvm_init_arch(&vmx_arch_ops, THIS_MODULE);
> + int r;
> +
> + vmx_io_bitmap = (char *) __get_free_pages(GFP_KERNEL, 1);
Why allocate two continuous pages instead of two separate pages for
IO_BITMAP_A and IO_BITMAP_B?
> + if (!vmx_io_bitmap) {
> + printk(KERN_ERR "kvm: vmx_io_bitmap allocation
> failed.\n");
> + r = -ENOMEM;
> + goto out;
> + }
> +
> + /*
> + * Allow direct access to the PC debug port (it is often used
> for I/O
> + * delays, but the vmexits simply slow things down).
> + */
> + memset(vmx_io_bitmap, ~0, 2 * PAGE_SIZE);
> + clear_bit(0x80, vmx_io_bitmap);
> +
> + r = kvm_init_arch(&vmx_arch_ops, THIS_MODULE);
> + if (r) {
> + goto out1;
> + }
> +
> + return 0;
> +
> +out1:
> + free_pages((unsigned long) vmx_io_bitmap, 1);
> +out:
> + return r;
> }
>
> static void __exit vmx_exit(void)
> {
> + if (vmx_io_bitmap)
> + free_pages((unsigned long) vmx_io_bitmap, 1);
Is there necessary to set vmx_io_bimap to NULL after free_page? And, I
assume that this
one should go to vmx member later.
Thanks,
Neo
> kvm_exit_arch();
> }
>
>
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