diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2025-04-12 13:55:49 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2025-08-18 14:23:07 +0200 |
| commit | 0e20f1f4c2cb77130cfe903a058a08883645dc4b (patch) | |
| tree | c6214bdf7c286398ac73d05878129099edbdffe7 /arch/x86/kernel/cpu | |
| parent | a1d34a444ce8c9a6ec4376247f80f0b777c6d3fe (diff) | |
x86/hyperv: Clean up hv_do_hypercall()
What used to be a simple few instructions has turned into a giant mess
(for x86_64). Not only does it use static_branch wrong, it mixes it
with dynamic branches for no apparent reason.
Notably it uses static_branch through an out-of-line function call,
which completely defeats the purpose, since instead of a simple
JMP/NOP site, you get a CALL+RET+TEST+Jcc sequence in return, which is
absolutely idiotic.
Add to that a dynamic test of hyperv_paravisor_present, something
which is set once and never changed.
Replace all this idiocy with a single direct function call to the
right hypercall variant.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Acked-by: Sean Christopherson <seanjc@google.com>
Link: https://lkml.kernel.org/r/20250714103440.897136093@infradead.org
Diffstat (limited to 'arch/x86/kernel/cpu')
| -rw-r--r-- | arch/x86/kernel/cpu/mshyperv.c | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index c78f860419d6..3c71effe9ff5 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -38,10 +38,6 @@ bool hv_nested; struct ms_hyperv_info ms_hyperv; -/* Used in modules via hv_do_hypercall(): see arch/x86/include/asm/mshyperv.h */ -bool hyperv_paravisor_present __ro_after_init; -EXPORT_SYMBOL_GPL(hyperv_paravisor_present); - #if IS_ENABLED(CONFIG_HYPERV) static inline unsigned int hv_get_nested_msr(unsigned int reg) { @@ -288,8 +284,18 @@ static void __init x86_setup_ops_for_tsc_pg_clock(void) old_restore_sched_clock_state = x86_platform.restore_sched_clock_state; x86_platform.restore_sched_clock_state = hv_restore_sched_clock_state; } + +#ifdef CONFIG_X86_64 +DEFINE_STATIC_CALL(hv_hypercall, hv_std_hypercall); +EXPORT_STATIC_CALL_TRAMP_GPL(hv_hypercall); +#define hypercall_update(hc) static_call_update(hv_hypercall, hc) +#endif #endif /* CONFIG_HYPERV */ +#ifndef hypercall_update +#define hypercall_update(hc) (void)hc +#endif + static uint32_t __init ms_hyperv_platform(void) { u32 eax; @@ -484,14 +490,14 @@ static void __init ms_hyperv_init_platform(void) ms_hyperv.shared_gpa_boundary = BIT_ULL(ms_hyperv.shared_gpa_boundary_bits); - hyperv_paravisor_present = !!ms_hyperv.paravisor_present; - pr_info("Hyper-V: Isolation Config: Group A 0x%x, Group B 0x%x\n", ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b); if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP) { static_branch_enable(&isolation_type_snp); + if (!ms_hyperv.paravisor_present) + hypercall_update(hv_snp_hypercall); } else if (hv_get_isolation_type() == HV_ISOLATION_TYPE_TDX) { static_branch_enable(&isolation_type_tdx); @@ -499,6 +505,7 @@ static void __init ms_hyperv_init_platform(void) ms_hyperv.hints &= ~HV_X64_APIC_ACCESS_RECOMMENDED; if (!ms_hyperv.paravisor_present) { + hypercall_update(hv_tdx_hypercall); /* * Mark the Hyper-V TSC page feature as disabled * in a TDX VM without paravisor so that the |