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x86/hyperv: fix invalid writes to MSRs during root partition kexec 

hyperv_cleanup resets the hypercall page by setting the MSR to 0. However,
the root partition is not allowed to write to the GPA bits of the MSR.
Instead, it uses the hypercall page provided by the MSR. Similar is the
case with the reference TSC MSR.

Clear only the enable bit instead of zeroing the entire MSR to make
the code valid for root partition too.

Signed-off-by: Anirudh Rayabharam <anrayabh@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20221027095729.1676394-3-anrayabh@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
This commit is contained in:
Anirudh Rayabharam 2022-10-27 15:27:29 +05:30 committed by Wei Liu
parent 4ad1aa5712
commit 2982635a0b
1 changed files with 7 additions and 4 deletions
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11
arch/x86/hyperv/hv_init.c
View File

@ -535,6 +535,7 @@ common_free:
void hyperv_cleanup(void)
{
union hv_x64_msr_hypercall_contents hypercall_msr;
union hv_reference_tsc_msr tsc_msr;
unregister_syscore_ops(&hv_syscore_ops);
@ -550,12 +551,14 @@ void hyperv_cleanup(void)
hv_hypercall_pg = NULL;
/* Reset the hypercall page */
hypercall_msr.as_uint64 = 0;
wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
hypercall_msr.as_uint64 = hv_get_register(HV_X64_MSR_HYPERCALL);
hypercall_msr.enable = 0;
hv_set_register(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
/* Reset the TSC page */
hypercall_msr.as_uint64 = 0;
wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
tsc_msr.as_uint64 = hv_get_register(HV_X64_MSR_REFERENCE_TSC);
tsc_msr.enable = 0;
hv_set_register(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
}
void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)