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Date: Thu, 5 Nov 2020 16:58:05 +0000 From: Wei Liu <wei.liu@...nel.org> To: Linux on Hyper-V List <linux-hyperv@...r.kernel.org> Cc: virtualization@...ts.linux-foundation.org, Linux Kernel List <linux-kernel@...r.kernel.org>, Michael Kelley <mikelley@...rosoft.com>, Vineeth Pillai <viremana@...ux.microsoft.com>, Sunil Muthuswamy <sunilmut@...rosoft.com>, Nuno Das Neves <nunodasneves@...ux.microsoft.com>, Wei Liu <wei.liu@...nel.org>, Lillian Grassin-Drake <ligrassi@...rosoft.com>, "K. Y. Srinivasan" <kys@...rosoft.com>, Haiyang Zhang <haiyangz@...rosoft.com>, Stephen Hemminger <sthemmin@...rosoft.com>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)), "H. Peter Anvin" <hpa@...or.com> Subject: [PATCH v2 08/17] x86/hyperv: handling hypercall page setup for root 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. Signed-off-by: Lillian Grassin-Drake <ligrassi@...rosoft.com> Signed-off-by: Sunil Muthuswamy <sunilmut@...rosoft.com> Signed-off-by: Nuno Das Neves <nunodasneves@...ux.microsoft.com> Co-Developed-by: Lillian Grassin-Drake <ligrassi@...rosoft.com> Co-Developed-by: Sunil Muthuswamy <sunilmut@...rosoft.com> Co-Developed-by: Nuno Das Neves <nunodasneves@...ux.microsoft.com> Signed-off-by: Wei Liu <wei.liu@...nel.org> --- 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); + 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 -- 2.20.1
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