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SubjectRE: [PATCH 06/15] hyperv: avoid unnecessary vmalloc
Date


> -----Original Message-----
> From: Roman Kagan [mailto:rkagan@virtuozzo.com]
> Sent: Tuesday, December 20, 2016 7:56 AM
> To: Paolo Bonzini <pbonzini@redhat.com>; Radim Krčmář
> <rkrcmar@redhat.com>; KY Srinivasan <kys@microsoft.com>; Vitaly
> Kuznetsov <vkuznets@redhat.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>; Ingo Molnar
> <mingo@redhat.com>; H. Peter Anvin <hpa@zytor.com>; x86@kernel.org;
> Haiyang Zhang <haiyangz@microsoft.com>; kvm@vger.kernel.org; linux-
> kernel@vger.kernel.org; devel@linuxdriverproject.org; Denis V . Lunev
> <den@openvz.org>; Roman Kagan <rkagan@virtuozzo.com>
> Subject: [PATCH 06/15] hyperv: avoid unnecessary vmalloc
>
> Make hypercall and tsc page allocation similar to the rest of the
> Hyper-V shared memory stuff instead of vmalloc-ing them.
>
> Also perform cleanup unconditionally which is safe.
>
> TODO: the skipping of free in case of a crash is probably no longer
> necessary, too.

Please breakup these patches.
>
> Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
> ---
> drivers/hv/hv.c | 42 ++++++++++++++++++------------------------
> 1 file changed, 18 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> index 6bbc0b09..b40c7d9 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -29,6 +29,7 @@
> #include <linux/version.h>
> #include <linux/interrupt.h>
> #include <linux/clockchips.h>
> +#include <asm/cacheflush.h>
> #include <asm/hyperv.h>
> #include <asm/mshyperv.h>
> #include "hyperv_vmbus.h"
> @@ -208,14 +209,15 @@ int hv_init(void)
> /* See if the hypercall page is already set */
> rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
>
> - virtaddr = __vmalloc(PAGE_SIZE, GFP_KERNEL,
> PAGE_KERNEL_EXEC);
> -
> - if (!virtaddr)
> + virtaddr = (void *)get_zeroed_page(GFP_KERNEL);
> + if (!virtaddr || set_memory_x((unsigned long)virtaddr, 1))
> goto cleanup;

Have you tested this patch.
> + hv_context.hypercall_page = virtaddr;
>
> hypercall_msr.enable = 1;
>
> - hypercall_msr.guest_physical_address = vmalloc_to_pfn(virtaddr);
> + hypercall_msr.guest_physical_address =
> + virt_to_phys(virtaddr) >> PAGE_SHIFT;
> wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
>
> /* Confirm that hypercall page did get setup. */
> @@ -225,14 +227,12 @@ int hv_init(void)
> if (!hypercall_msr.enable)
> goto cleanup;
>
> - hv_context.hypercall_page = virtaddr;
> -
> #ifdef CONFIG_X86_64
> if (ms_hyperv.features &
> HV_X64_MSR_REFERENCE_TSC_AVAILABLE) {
> union hv_x64_msr_hypercall_contents tsc_msr;
> void *va_tsc;
>
> - va_tsc = __vmalloc(PAGE_SIZE, GFP_KERNEL,
> PAGE_KERNEL);
> + va_tsc = (void *)get_zeroed_page(GFP_KERNEL);
> if (!va_tsc)
> goto cleanup;
> hv_context.tsc_page = va_tsc;
> @@ -240,7 +240,8 @@ int hv_init(void)
> rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
>
> tsc_msr.enable = 1;
> - tsc_msr.guest_physical_address = vmalloc_to_pfn(va_tsc);
> + tsc_msr.guest_physical_address =
> + virt_to_phys(va_tsc) >> PAGE_SHIFT;
>
> wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
> clocksource_register_hz(&hyperv_cs_tsc,
> NSEC_PER_SEC/100);
> @@ -249,14 +250,9 @@ int hv_init(void)
> return 0;
>
> cleanup:
> - if (virtaddr) {
> - if (hypercall_msr.enable) {
> - hypercall_msr.as_uint64 = 0;
> - wrmsrl(HV_X64_MSR_HYPERCALL,
> hypercall_msr.as_uint64);
> - }
> -
> - vfree(virtaddr);
> - }
> + hypercall_msr.as_uint64 = 0;
> + wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> + free_page((unsigned long)virtaddr);
>
> return -ENOTSUPP;
> }
> @@ -273,13 +269,11 @@ void hv_cleanup(bool crash)
> /* Reset our OS id */
> wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
>
> - if (hv_context.hypercall_page) {
> - hypercall_msr.as_uint64 = 0;
> - wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> - if (!crash)
> - vfree(hv_context.hypercall_page);
> - hv_context.hypercall_page = NULL;
> - }
> + hypercall_msr.as_uint64 = 0;
> + wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> + if (!crash)
> + free_page((unsigned long)hv_context.hypercall_page);
> + hv_context.hypercall_page = NULL;
>
> #ifdef CONFIG_X86_64
> /*
> @@ -298,7 +292,7 @@ void hv_cleanup(bool crash)
> hypercall_msr.as_uint64 = 0;
> wrmsrl(HV_X64_MSR_REFERENCE_TSC,
> hypercall_msr.as_uint64);
> if (!crash)
> - vfree(hv_context.tsc_page);
> + free_page((unsigned long)hv_context.tsc_page);
> hv_context.tsc_page = NULL;
> }
> #endif
> --
> 2.9.3

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