> From: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
> Sent: Monday, November 21, 2022 4:01 PM
> [...]
> On Mon, Nov 21, 2022 at 11:51:47AM -0800, Dexuan Cui wrote:
> [...]
> I'm not convinced it deserves a separate helper for one user.
> Does it look that ugly if tdx_map_gpa() uses __tdx_hypercall() directly?
Will use __tdx_hypercall() directly.
> > /* Called from __tdx_hypercall() for unrecoverable failure */
> > void __tdx_hypercall_failed(void)
> > {
> > @@ -691,6 +712,43 @@ static bool try_accept_one(phys_addr_t *start,
> unsigned long len,
> > return true;
> > }
> >
> > +/*
> > + * Notify the VMM about page mapping conversion. More info about ABI
> > + * can be found in TDX Guest-Host-Communication Interface (GHCI),
> > + * section "TDG.VP.VMCALL<MapGPA>"
> > + */
> > +static bool tdx_map_gpa(phys_addr_t start, phys_addr_t end, bool enc)
> > +{
> > + u64 ret, r11;
> > +
> > + while (1) {
>
> Endless? Maybe an upper limit if no progress?
I'll add a max count of 1000, which should be far more than enough.
> > + ret = _tdx_hypercall_output_r11(TDVMCALL_MAP_GPA, start,
> > + end - start, 0, 0, &r11);
> > + if (!ret)
> > + break;
> > +
> > + if (ret != TDVMCALL_STATUS_RETRY)
> > + break;
> > +
> > + /*
> > + * The guest must retry the operation for the pages in the
> > + * region starting at the GPA specified in R11. Make sure R11
> > + * contains a sane value.
> > + */
> > + if ((r11 & ~cc_mkdec(0)) < (start & ~cc_mkdec(0)) ||
> > + (r11 & ~cc_mkdec(0)) >= (end & ~cc_mkdec(0)))
> > + return false;
>
> Emm. All of them suppose to have shared bit set, why not compare directly
> without cc_mkdec() dance?
The above code is unnecessary and will be removed.
So, I'll use the below in v2:
/*
* Notify the VMM about page mapping conversion. More info about ABI
* can be found in TDX Guest-Host-Communication Interface (GHCI),
* section "TDG.VP.VMCALL<MapGPA>"
*/
static bool tdx_map_gpa(phys_addr_t start, phys_addr_t end, bool enc)
{
int max_retry_cnt = 1000, retry_cnt = 0;
struct tdx_hypercall_args args;
u64 map_fail_paddr, ret;
while (1) {
args.r10 = TDX_HYPERCALL_STANDARD;
args.r11 = TDVMCALL_MAP_GPA;
args.r12 = start;
args.r13 = end - start;
args.r14 = 0;
args.r15 = 0;
ret = __tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT);
if (!ret)
break;
if (ret != TDVMCALL_STATUS_RETRY)
break;
/*
* The guest must retry the operation for the pages in the
* region starting at the GPA specified in R11. Make sure R11
* contains a sane value.
*/
map_fail_paddr = args.r11 ;
if (map_fail_paddr < start || map_fail_paddr >= end)
return false;
if (map_fail_paddr == start) {
retry_cnt++;
if (retry_cnt > max_retry_cnt)
return false;
} else {
retry_cnt = 0;;
start = map_fail_paddr;
}
}
return !ret;
}
