Messages in this thread | | | Date | Wed, 6 Oct 2021 12:49:10 -0700 | From | Josh Poimboeuf <> | Subject | Re: [PATCH v8 09/11] x86/tdx: Add MSR support for TDX guest |
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On Mon, Oct 04, 2021 at 07:52:03PM -0700, Kuppuswamy Sathyanarayanan wrote: > diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c > index 3d0416515506..062ac4720434 100644 > --- a/arch/x86/kernel/tdx.c > +++ b/arch/x86/kernel/tdx.c > @@ -110,6 +110,41 @@ static __cpuidle void tdx_safe_halt(void) > _tdx_halt(irq_disabled, do_sti); > } > > +static u64 tdx_read_msr_safe(unsigned int msr, int *err)
Here the kernel convention would probably be to return the error and make 'val' an argument:
static int tdx_read_msr_safe(unsigned int msr, u64 *val)
> +{ > + struct tdx_hypercall_output out = {0}; > + u64 ret; > + > + /* > + * Emulate the MSR read via hypercall. More info about ABI > + * can be found in TDX Guest-Host-Communication Interface > + * (GHCI), sec titled "TDG.VP.VMCALL<Instruction.RDMSR>". > + */ > + ret = _tdx_hypercall(EXIT_REASON_MSR_READ, msr, 0, 0, 0, &out); > + > + *err = ret ? -EIO : 0; > + > + return out.r11; > +} > + > +static int tdx_write_msr_safe(unsigned int msr, unsigned int low, > + unsigned int high) > +{ > + u64 ret; > + > + WARN_ON_ONCE(tdx_is_context_switched_msr(msr));
This fails to build, tdx_is_context_switched_msr() is missing.
> @@ -136,19 +171,33 @@ unsigned long tdx_get_ve_info(struct ve_info *ve) > int tdx_handle_virtualization_exception(struct pt_regs *regs, > struct ve_info *ve) > { > + unsigned long val; > + int ret = 0; > + > switch (ve->exit_reason) { > case EXIT_REASON_HLT: > tdx_halt(); > break; > + case EXIT_REASON_MSR_READ: > + val = tdx_read_msr_safe(regs->cx, (unsigned int *)&ret);
Why the 'unsigned int *' cast?
Also, 'val' should have the same type as the one returned by tdx_read_msr_safe(). (Though it technically doesn't matter here.)
-- Josh
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