On 12/6/22 4:33 PM, Dexuan Cui wrote: > From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> > > So far __tdx_hypercall() only handles six arguments for VMCALL. > Expanding it to six more register would allow to cover more use-cases. > > Using RDI and RSI as VMCALL arguments requires more register shuffling. > RAX is used to hold tdx_hypercall_args pointer and RBP stores flags. > > While there, fix typo in the comment on panic branch. > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > Reviewed-by: Dexuan Cui <decui@xxxxxxxxxxxxx> > Tested-by: Dexuan Cui <decui@xxxxxxxxxxxxx> > --- > > This patch is from Kirill. I'm posting the patch on behalf him: > https://lwn.net/ml/linux-kernel/20221202214741.7vfmqgvgubxqffen@xxxxxxxxxxxxxxxxx/ > > This is actually v1, but let's use v2 in the Subject to be consistent > with the Subjects of the other patches. > > arch/x86/coco/tdx/tdcall.S | 82 ++++++++++++++++++++++--------- > arch/x86/include/asm/shared/tdx.h | 6 +++ > arch/x86/kernel/asm-offsets.c | 6 +++ > 3 files changed, 70 insertions(+), 24 deletions(-) > > diff --git a/arch/x86/coco/tdx/tdcall.S b/arch/x86/coco/tdx/tdcall.S > index f9eb1134f22d..64e57739dc9d 100644 > --- a/arch/x86/coco/tdx/tdcall.S > +++ b/arch/x86/coco/tdx/tdcall.S > @@ -13,6 +13,12 @@ > /* > * Bitmasks of exposed registers (with VMM). > */ > +#define TDX_RDX BIT(2) > +#define TDX_RBX BIT(3) > +#define TDX_RSI BIT(6) > +#define TDX_RDI BIT(7) > +#define TDX_R8 BIT(8) > +#define TDX_R9 BIT(9) > #define TDX_R10 BIT(10) > #define TDX_R11 BIT(11) > #define TDX_R12 BIT(12) > @@ -27,9 +33,9 @@ > * details can be found in TDX GHCI specification, section > * titled "TDCALL [TDG.VP.VMCALL] leaf". > */ > -#define TDVMCALL_EXPOSE_REGS_MASK ( TDX_R10 | TDX_R11 | \ > - TDX_R12 | TDX_R13 | \ > - TDX_R14 | TDX_R15 ) > +#define TDVMCALL_EXPOSE_REGS_MASK \ > + ( TDX_RDX | TDX_RBX | TDX_RSI | TDX_RDI | TDX_R8 | TDX_R9 | \ > + TDX_R10 | TDX_R11 | TDX_R12 | TDX_R13 | TDX_R14 | TDX_R15 ) > You seem to have expanded the list to include all VMCALL supported registers except RBP. Why not include it as well? That way, it will be a complete support. > /* > * __tdx_module_call() - Used by TDX guests to request services from > @@ -124,19 +130,32 @@ SYM_FUNC_START(__tdx_hypercall) > push %r14 > push %r13 > push %r12 > + push %rbx > + push %rbp > + > + movq %rdi, %rax > + movq %rsi, %rbp > + > + /* Copy hypercall registers from arg struct: */ > + movq TDX_HYPERCALL_r8(%rax), %r8 > + movq TDX_HYPERCALL_r9(%rax), %r9 > + movq TDX_HYPERCALL_r10(%rax), %r10 > + movq TDX_HYPERCALL_r11(%rax), %r11 > + movq TDX_HYPERCALL_r12(%rax), %r12 > + movq TDX_HYPERCALL_r13(%rax), %r13 > + movq TDX_HYPERCALL_r14(%rax), %r14 > + movq TDX_HYPERCALL_r15(%rax), %r15 > + movq TDX_HYPERCALL_rdi(%rax), %rdi > + movq TDX_HYPERCALL_rsi(%rax), %rsi > + movq TDX_HYPERCALL_rbx(%rax), %rbx > + movq TDX_HYPERCALL_rdx(%rax), %rdx > + > + push %rax > > /* Mangle function call ABI into TDCALL ABI: */ > /* Set TDCALL leaf ID (TDVMCALL (0)) in RAX */ > xor %eax, %eax > > - /* Copy hypercall registers from arg struct: */ > - movq TDX_HYPERCALL_r10(%rdi), %r10 > - movq TDX_HYPERCALL_r11(%rdi), %r11 > - movq TDX_HYPERCALL_r12(%rdi), %r12 > - movq TDX_HYPERCALL_r13(%rdi), %r13 > - movq TDX_HYPERCALL_r14(%rdi), %r14 > - movq TDX_HYPERCALL_r15(%rdi), %r15 > - > movl $TDVMCALL_EXPOSE_REGS_MASK, %ecx > > /* > @@ -148,14 +167,14 @@ SYM_FUNC_START(__tdx_hypercall) > * HLT operation indefinitely. Since this is the not the desired > * result, conditionally call STI before TDCALL. > */ > - testq $TDX_HCALL_ISSUE_STI, %rsi > + testq $TDX_HCALL_ISSUE_STI, %rbp > jz .Lskip_sti > sti > .Lskip_sti: > tdcall > > /* > - * RAX==0 indicates a failure of the TDVMCALL mechanism itself and that > + * RAX!=0 indicates a failure of the TDVMCALL mechanism itself and that > * something has gone horribly wrong with the TDX module. > * > * The return status of the hypercall operation is in a separate > @@ -165,30 +184,45 @@ SYM_FUNC_START(__tdx_hypercall) > testq %rax, %rax > jne .Lpanic > > - /* TDVMCALL leaf return code is in R10 */ > - movq %r10, %rax > + pop %rax > > /* Copy hypercall result registers to arg struct if needed */ > - testq $TDX_HCALL_HAS_OUTPUT, %rsi > + testq $TDX_HCALL_HAS_OUTPUT, %rbp > jz .Lout > > - movq %r10, TDX_HYPERCALL_r10(%rdi) > - movq %r11, TDX_HYPERCALL_r11(%rdi) > - movq %r12, TDX_HYPERCALL_r12(%rdi) > - movq %r13, TDX_HYPERCALL_r13(%rdi) > - movq %r14, TDX_HYPERCALL_r14(%rdi) > - movq %r15, TDX_HYPERCALL_r15(%rdi) > + movq %r8, TDX_HYPERCALL_r8(%rax) > + movq %r9, TDX_HYPERCALL_r9(%rax) > + movq %r10, TDX_HYPERCALL_r10(%rax) > + movq %r11, TDX_HYPERCALL_r11(%rax) > + movq %r12, TDX_HYPERCALL_r12(%rax) > + movq %r13, TDX_HYPERCALL_r13(%rax) > + movq %r14, TDX_HYPERCALL_r14(%rax) > + movq %r15, TDX_HYPERCALL_r15(%rax) > + movq %rdi, TDX_HYPERCALL_rdi(%rax) > + movq %rsi, TDX_HYPERCALL_rsi(%rax) > + movq %rbx, TDX_HYPERCALL_rbx(%rax) > + movq %rdx, TDX_HYPERCALL_rdx(%rax) > .Lout: > + /* TDVMCALL leaf return code is in R10 */ > + movq %r10, %rax > + > /* > * Zero out registers exposed to the VMM to avoid speculative execution > * with VMM-controlled values. This needs to include all registers > - * present in TDVMCALL_EXPOSE_REGS_MASK (except R12-R15). R12-R15 > - * context will be restored. > + * present in TDVMCALL_EXPOSE_REGS_MASK, except RBX, and R12-R15 which > + * will be restored. > */ > + xor %r8d, %r8d > + xor %r9d, %r9d > xor %r10d, %r10d > xor %r11d, %r11d > + xor %rdi, %rdi > + xor %rsi, %rsi > + xor %rdx, %rdx > > /* Restore callee-saved GPRs as mandated by the x86_64 ABI */ > + pop %rbp > + pop %rbx > pop %r12 > pop %r13 > pop %r14 > diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h > index e53f26228fbb..8068faa52de1 100644 > --- a/arch/x86/include/asm/shared/tdx.h > +++ b/arch/x86/include/asm/shared/tdx.h > @@ -22,12 +22,18 @@ > * This is a software only structure and not part of the TDX module/VMM ABI. > */ > struct tdx_hypercall_args { > + u64 r8; > + u64 r9; > u64 r10; > u64 r11; > u64 r12; > u64 r13; > u64 r14; > u64 r15; > + u64 rdi; > + u64 rsi; > + u64 rbx; > + u64 rdx; > }; > > /* Used to request services from the VMM */ > diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c > index 437308004ef2..9f09947495e2 100644 > --- a/arch/x86/kernel/asm-offsets.c > +++ b/arch/x86/kernel/asm-offsets.c > @@ -75,12 +75,18 @@ static void __used common(void) > OFFSET(TDX_MODULE_r11, tdx_module_output, r11); > > BLANK(); > + OFFSET(TDX_HYPERCALL_r8, tdx_hypercall_args, r8); > + OFFSET(TDX_HYPERCALL_r9, tdx_hypercall_args, r9); > OFFSET(TDX_HYPERCALL_r10, tdx_hypercall_args, r10); > OFFSET(TDX_HYPERCALL_r11, tdx_hypercall_args, r11); > OFFSET(TDX_HYPERCALL_r12, tdx_hypercall_args, r12); > OFFSET(TDX_HYPERCALL_r13, tdx_hypercall_args, r13); > OFFSET(TDX_HYPERCALL_r14, tdx_hypercall_args, r14); > OFFSET(TDX_HYPERCALL_r15, tdx_hypercall_args, r15); > + OFFSET(TDX_HYPERCALL_rdi, tdx_hypercall_args, rdi); > + OFFSET(TDX_HYPERCALL_rsi, tdx_hypercall_args, rsi); > + OFFSET(TDX_HYPERCALL_rbx, tdx_hypercall_args, rbx); > + OFFSET(TDX_HYPERCALL_rdx, tdx_hypercall_args, rdx); > > BLANK(); > OFFSET(BP_scratch, boot_params, scratch); -- Sathyanarayanan Kuppuswamy Linux Kernel Developer
