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    SubjectRe: [PATCH v10 05/16] x86/virt/tdx: Add skeleton to enable TDX on demand
    On Tue, Mar 07, 2023 at 03:13:50AM +1300,
    Kai Huang <kai.huang@intel.com> wrote:

    > +static int try_init_module_global(void)
    > +{
    > + int ret;
    > +
    > + /*
    > + * The TDX module global initialization only needs to be done
    > + * once on any cpu.
    > + */
    > + spin_lock(&tdx_global_init_lock);


    If I use tdx_cpu_enable() via kvm hardware_enable_all(), this function is called
    in the context IPI callback and the lockdep complains. Here is my patch to
    address it

    From 0c4022ffe8cd68dfb455c418eb65538e4e100115 Mon Sep 17 00:00:00 2001
    Message-Id: <0c4022ffe8cd68dfb455c418eb65538e4e100115.1678926123.git.isaku.yamahata@intel.com>
    In-Reply-To: <d2aa2142665b8204b628232ab615c98090371c99.1678926122.git.isaku.yamahata@intel.com>
    References: <d2aa2142665b8204b628232ab615c98090371c99.1678926122.git.isaku.yamahata@intel.com>
    From: Isaku Yamahata <isaku.yamahata@intel.com>
    Date: Wed, 15 Mar 2023 14:26:37 -0700
    Subject: [PATCH] x86/virt/vmx/tdx: Use raw spin lock instead of spin lock

    tdx_cpu_enable() can be called by IPI handler. The lockdep complains about
    spin lock as follows. Use raw spin lock.

    =============================
    [ BUG: Invalid wait context ]
    6.3.0-rc1-tdx-kvm-upstream+ #389 Not tainted
    -----------------------------
    swapper/154/0 is trying to lock:
    ffffffffa7875e58 (tdx_global_init_lock){....}-{3:3}, at: tdx_cpu_enable+0x67/0x180
    other info that might help us debug this:
    context-{2:2}
    no locks held by swapper/154/0.
    stack backtrace:
    Call Trace:
    <IRQ>
    dump_stack_lvl+0x64/0xb0
    dump_stack+0x10/0x20
    __lock_acquire+0x912/0xc30
    lock_acquire.part.0+0x99/0x220
    lock_acquire+0x60/0x170
    _raw_spin_lock_irqsave+0x43/0x70
    tdx_cpu_enable+0x67/0x180
    vt_hardware_enable+0x3b/0x60
    kvm_arch_hardware_enable+0xe7/0x2e0
    hardware_enable_nolock+0x33/0x80
    __flush_smp_call_function_queue+0xc4/0x590
    generic_smp_call_function_single_interrupt+0x1a/0xb0
    __sysvec_call_function+0x48/0x200
    sysvec_call_function+0xad/0xd0
    </IRQ>

    Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
    ---
    arch/x86/virt/vmx/tdx/tdx.c | 7 ++++---
    1 file changed, 4 insertions(+), 3 deletions(-)

    diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
    index 2ee37a5dedcf..e1c8ffad7406 100644
    --- a/arch/x86/virt/vmx/tdx/tdx.c
    +++ b/arch/x86/virt/vmx/tdx/tdx.c
    @@ -41,7 +41,7 @@ static u32 tdx_guest_keyid_start __ro_after_init;
    static u32 tdx_nr_guest_keyids __ro_after_init;

    static unsigned int tdx_global_init_status;
    -static DEFINE_SPINLOCK(tdx_global_init_lock);
    +static DEFINE_RAW_SPINLOCK(tdx_global_init_lock);
    #define TDX_GLOBAL_INIT_DONE _BITUL(0)
    #define TDX_GLOBAL_INIT_FAILED _BITUL(1)

    @@ -349,6 +349,7 @@ static void tdx_trace_seamcalls(u64 level)

    static int try_init_module_global(void)
    {
    + unsigned long flags;
    u64 tsx_ctrl;
    int ret;

    @@ -356,7 +357,7 @@ static int try_init_module_global(void)
    * The TDX module global initialization only needs to be done
    * once on any cpu.
    */
    - spin_lock(&tdx_global_init_lock);
    + raw_spin_lock_irqsave(&tdx_global_init_lock, flags);

    if (tdx_global_init_status & TDX_GLOBAL_INIT_DONE) {
    ret = tdx_global_init_status & TDX_GLOBAL_INIT_FAILED ?
    @@ -373,7 +374,7 @@ static int try_init_module_global(void)
    if (ret)
    tdx_global_init_status |= TDX_GLOBAL_INIT_FAILED;
    out:
    - spin_unlock(&tdx_global_init_lock);
    + raw_spin_unlock_irqrestore(&tdx_global_init_lock, flags);

    if (ret) {
    if (trace_boot_seamcalls)
    --
    2.25.1

    --
    Isaku Yamahata <isaku.yamahata@gmail.com>

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