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    Subject[PATCH v6 07/16] x86/hyperv: handling hypercall page setup for root
    Date
    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.

    Add checks to hv_suspend & co to bail early because they are not
    supported in this setup yet.

    Signed-off-by: Lillian Grassin-Drake <ligrassi@microsoft.com>
    Signed-off-by: Sunil Muthuswamy <sunilmut@microsoft.com>
    Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
    Co-Developed-by: Lillian Grassin-Drake <ligrassi@microsoft.com>
    Co-Developed-by: Sunil Muthuswamy <sunilmut@microsoft.com>
    Co-Developed-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
    Signed-off-by: Wei Liu <wei.liu@kernel.org>
    Reviewed-by: Michael Kelley <mikelley@microsoft.com>
    ---
    v3:
    1. Use HV_HYP_PAGE_SIZE.
    2. Add checks to hv_suspend & co.
    ---
    arch/x86/hyperv/hv_init.c | 37 ++++++++++++++++++++++++++++++++++---
    1 file changed, 34 insertions(+), 3 deletions(-)

    diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
    index 5b90a7290177..11c5997691f4 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>

    u64 hv_current_partition_id = ~0ull;
    EXPORT_SYMBOL_GPL(hv_current_partition_id);
    @@ -283,6 +284,9 @@ static int hv_suspend(void)
    union hv_x64_msr_hypercall_contents hypercall_msr;
    int ret;

    + if (hv_root_partition)
    + return -EPERM;
    +
    /*
    * Reset the hypercall page as it is going to be invalidated
    * accross hibernation. Setting hv_hypercall_pg to NULL ensures
    @@ -432,8 +436,35 @@ 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, HV_HYP_PAGE_SIZE);
    + 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
    @@ -576,6 +607,6 @@ EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);

    bool hv_is_hibernation_supported(void)
    {
    - return acpi_sleep_state_supported(ACPI_STATE_S4);
    + return !hv_root_partition && acpi_sleep_state_supported(ACPI_STATE_S4);
    }
    EXPORT_SYMBOL_GPL(hv_is_hibernation_supported);
    --
    2.20.1
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