[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <87v9gfjpoi.fsf@vitty.brq.redhat.com>
Date: Tue, 15 Sep 2020 12:32:29 +0200
From: Vitaly Kuznetsov <vkuznets@...hat.com>
To: Wei Liu <wei.liu@...nel.org>,
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 <nudasnev@...rosoft.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>,
"maintainer\:X86 ARCHITECTURE \(32-BIT AND 64-BIT\)" <x86@...nel.org>,
"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH RFC v1 08/18] x86/hyperv: handling hypercall page setup for root
Wei Liu <wei.liu@...nel.org> 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.
And we can't setup a new hypercall page by writing something different
to HV_X64_MSR_HYPERCALL, right?
>
> 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 <nudasnev@...rosoft.com>
> Co-Developed-by: Lillian Grassin-Drake <ligrassi@...rosoft.com>
> Co-Developed-by: Sunil Muthuswamy <sunilmut@...rosoft.com>
> Co-Developed-by: Nuno Das Neves <nudasnev@...rosoft.com>
> Signed-off-by: Wei Liu <wei.liu@...nel.org>
> ---
> arch/x86/hyperv/hv_init.c | 26 ++++++++++++++++++++++++--
> 1 file changed, 24 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index 0eec1ed32023..26233aebc86c 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;
> @@ -448,8 +449,29 @@ 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;
> +
> + /*
> + * 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);
memremap() can fail...
> + 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);
> + }
Why can't we do wrmsrl() for both cases here?
>
> /*
> * Ignore any errors in setting up stimer clockevents
--
Vitaly
Powered by blists - more mailing lists