Wei Liu <wei.liu@xxxxxxxxxx> writes:
> When Linux is running as the root partition, the hypercall page will
> have already been setup by Hyper-V. Copy the content over to the
> allocated page.
>
> The suspend, resume and cleanup paths remain untouched because they are
> not supported in this setup yet.
What about adding BUG_ONs there then?
>
> Signed-off-by: Lillian Grassin-Drake <ligrassi@xxxxxxxxxxxxx>
> Signed-off-by: Sunil Muthuswamy <sunilmut@xxxxxxxxxxxxx>
> Signed-off-by: Nuno Das Neves <nunodasneves@xxxxxxxxxxxxxxxxxxx>
> Co-Developed-by: Lillian Grassin-Drake <ligrassi@xxxxxxxxxxxxx>
> Co-Developed-by: Sunil Muthuswamy <sunilmut@xxxxxxxxxxxxx>
> Co-Developed-by: Nuno Das Neves <nunodasneves@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Wei Liu <wei.liu@xxxxxxxxxx>
> ---
> arch/x86/hyperv/hv_init.c | 32 ++++++++++++++++++++++++++++++--
> 1 file changed, 30 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index 73b0fb851f76..9fcaf741be99 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -25,6 +25,7 @@
> #include <linux/cpuhotplug.h>
> #include <linux/syscore_ops.h>
> #include <clocksource/hyperv_timer.h>
> +#include <linux/highmem.h>
>
> /* Is Linux running as the root partition? */
> bool hv_root_partition;
> @@ -438,8 +439,35 @@ void __init hyperv_init(void)
>
> rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> hypercall_msr.enable = 1;
> - hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
> - wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> +
> + if (hv_root_partition) {
> + struct page *pg;
> + void *src, *dst;
> +
> + /*
> + * For the root partition, the hypervisor will set up its
> + * hypercall page. The hypervisor guarantees it will not show
> + * up in the root's address space. The root can't change the
> + * location of the hypercall page.
> + *
> + * Order is important here. We must enable the hypercall page
> + * so it is populated with code, then copy the code to an
> + * executable page.
> + */
> + wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> +
> + pg = vmalloc_to_page(hv_hypercall_pg);
> + dst = kmap(pg);
> + src = memremap(hypercall_msr.guest_physical_address << PAGE_SHIFT, PAGE_SIZE,
> + MEMREMAP_WB);
> + BUG_ON(!(src && dst));
> + memcpy(dst, src, PAGE_SIZE);
Super-nit: while on x86 PAGE_SIZE always matches HV_HYP_PAGE_SIZE, would
it be more accurate to use the later here?
> + memunmap(src);
> + kunmap(pg);
> + } else {
> + hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
> + wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> + }
>
> /*
> * Ignore any errors in setting up stimer clockevents
--
Vitaly
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