diff options
| author | Dexuan Cui <decui@microsoft.com> | 2023-08-24 01:07:09 -0700 |
|---|---|---|
| committer | Wei Liu <wei.liu@kernel.org> | 2023-08-25 00:04:57 +0000 |
| commit | 23378295042a4bcaeec350733a4771678e7a1f3a (patch) | |
| tree | 96e4447fe9da4a905966d611f98ace45fb4ea714 /arch/x86/hyperv/hv_init.c | |
| parent | d3a9d7e49d15316f68f4347f48adcd1665834980 (diff) | |
Drivers: hv: vmbus: Bring the post_msg_page back for TDX VMs with the paravisor
The post_msg_page was removed in
commit 9a6b1a170ca8 ("Drivers: hv: vmbus: Remove the per-CPU post_msg_page")
However, it turns out that we need to bring it back, but only for a TDX VM
with the paravisor: in such a VM, the hyperv_pcpu_input_arg is not decrypted,
but the HVCALL_POST_MESSAGE in such a VM needs a decrypted page as the
hypercall input page: see the comments in hyperv_init() for a detailed
explanation.
Except for HVCALL_POST_MESSAGE and HVCALL_SIGNAL_EVENT, the other hypercalls
in a TDX VM with the paravisor still use hv_hypercall_pg and must use the
hyperv_pcpu_input_arg (which is encrypted in such a VM), when a hypercall
input page is used.
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Tianyu Lan <tiala@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Link: https://lore.kernel.org/r/20230824080712.30327-8-decui@microsoft.com
Diffstat (limited to 'arch/x86/hyperv/hv_init.c')
| -rw-r--r-- | arch/x86/hyperv/hv_init.c | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index eca5c4b7e3b5..3729eee21e47 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -480,6 +480,22 @@ void __init hyperv_init(void) * Setup the hypercall page and enable hypercalls. * 1. Register the guest ID * 2. Enable the hypercall and register the hypercall page + * + * A TDX VM with no paravisor only uses TDX GHCI rather than hv_hypercall_pg: + * when the hypercall input is a page, such a VM must pass a decrypted + * page to Hyper-V, e.g. hv_post_message() uses the per-CPU page + * hyperv_pcpu_input_arg, which is decrypted if no paravisor is present. + * + * A TDX VM with the paravisor uses hv_hypercall_pg for most hypercalls, + * which are handled by the paravisor and the VM must use an encrypted + * input page: in such a VM, the hyperv_pcpu_input_arg is encrypted and + * used in the hypercalls, e.g. see hv_mark_gpa_visibility() and + * hv_arch_irq_unmask(). Such a VM uses TDX GHCI for two hypercalls: + * 1. HVCALL_SIGNAL_EVENT: see vmbus_set_event() and _hv_do_fast_hypercall8(). + * 2. HVCALL_POST_MESSAGE: the input page must be a decrypted page, i.e. + * hv_post_message() in such a VM can't use the encrypted hyperv_pcpu_input_arg; + * instead, hv_post_message() uses the post_msg_page, which is decrypted + * in such a VM and is only used in such a VM. */ guest_id = hv_generate_guest_id(LINUX_VERSION_CODE); wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); @@ -487,8 +503,8 @@ void __init hyperv_init(void) /* Hyper-V requires to write guest os id via ghcb in SNP IVM. */ hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, guest_id); - /* A TDX guest uses the GHCI call rather than hv_hypercall_pg. */ - if (hv_isolation_type_tdx()) + /* A TDX VM with no paravisor only uses TDX GHCI rather than hv_hypercall_pg */ + if (hv_isolation_type_tdx() && !ms_hyperv.paravisor_present) goto skip_hypercall_pg_init; hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START, |