From: Dexuan Cui <decui@microsoft.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: "ak@linux.intel.com" <ak@linux.intel.com>,
"arnd@arndb.de" <arnd@arndb.de>, "bp@alien8.de" <bp@alien8.de>,
"brijesh.singh@amd.com" <brijesh.singh@amd.com>,
"Williams, Dan J" <dan.j.williams@intel.com>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
"hpa@zytor.com" <hpa@zytor.com>,
"jane.chu@oracle.com" <jane.chu@oracle.com>,
"kirill.shutemov@linux.intel.com"
<kirill.shutemov@linux.intel.com>,
KY Srinivasan <kys@microsoft.com>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"luto@kernel.org" <luto@kernel.org>,
"mingo@redhat.com" <mingo@redhat.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"rostedt@goodmis.org" <rostedt@goodmis.org>,
"sathyanarayanan.kuppuswamy@linux.intel.com"
<sathyanarayanan.kuppuswamy@linux.intel.com>,
"seanjc@google.com" <seanjc@google.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"tony.luck@intel.com" <tony.luck@intel.com>,
"wei.liu@kernel.org" <wei.liu@kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 2/6] x86/tdx: Retry TDVMCALL_MAP_GPA() when needed
Date: Wed, 23 Nov 2022 03:27:25 +0000 [thread overview]
Message-ID: <SA1PR21MB133596B911C6A45142B83B52BF0C9@SA1PR21MB1335.namprd21.prod.outlook.com> (raw)
In-Reply-To: <20221122000100.bizske6iltfgdwcu@box.shutemov.name>
> From: Kirill A. Shutemov <kirill@shutemov.name>
> 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;
}
next prev parent reply other threads:[~2022-11-23 3:27 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-21 19:51 [PATCH 0/6] Support TDX guests on Hyper-V Dexuan Cui
2022-11-21 19:51 ` [PATCH 1/6] x86/tdx: Support hypercalls for " Dexuan Cui
2022-11-21 20:38 ` Dave Hansen
2022-11-21 23:52 ` Kirill A. Shutemov
2022-11-23 1:37 ` Dexuan Cui
2022-11-23 1:56 ` Dexuan Cui
2022-11-23 16:04 ` Dave Hansen
2022-11-23 18:59 ` Dexuan Cui
2022-11-23 3:52 ` Sathyanarayanan Kuppuswamy
2022-11-23 14:40 ` Kirill A. Shutemov
2022-11-23 18:55 ` Dexuan Cui
2022-11-30 19:14 ` Dexuan Cui
2022-12-02 21:47 ` 'Kirill A. Shutemov'
2022-11-23 16:03 ` Dave Hansen
2022-11-21 19:51 ` [PATCH 2/6] x86/tdx: Retry TDVMCALL_MAP_GPA() when needed Dexuan Cui
2022-11-21 20:55 ` Dave Hansen
2022-11-23 2:55 ` Dexuan Cui
2022-11-22 0:01 ` Kirill A. Shutemov
2022-11-23 3:27 ` Dexuan Cui [this message]
2022-11-23 13:30 ` Michael Kelley (LINUX)
2022-11-28 0:07 ` Dexuan Cui
2022-11-21 19:51 ` [PATCH 3/6] x86/tdx: Support vmalloc() for tdx_enc_status_changed() Dexuan Cui
2022-11-21 21:00 ` Dave Hansen
2022-11-23 4:01 ` Dexuan Cui
2022-11-22 0:24 ` Kirill A. Shutemov
2022-11-23 23:51 ` Dexuan Cui
2022-11-24 7:51 ` Kirill A. Shutemov
2022-11-27 20:27 ` Dexuan Cui
2022-11-21 19:51 ` [PATCH 4/6] x86/hyperv: Add hv_isolation_type_tdx() to detect TDX guests Dexuan Cui
2022-11-21 21:01 ` Dave Hansen
2022-11-21 21:48 ` Borislav Petkov
2022-11-22 0:32 ` Sathyanarayanan Kuppuswamy
2022-11-23 19:13 ` Dexuan Cui
2022-11-21 19:51 ` [PATCH 5/6] x86/hyperv: Support hypercalls for " Dexuan Cui
2022-11-21 20:05 ` Dave Hansen
2022-11-23 2:14 ` Dexuan Cui
2022-11-23 14:47 ` Kirill A. Shutemov
2022-11-23 18:13 ` Dexuan Cui
2022-11-23 18:18 ` Sathyanarayanan Kuppuswamy
2022-11-23 19:07 ` Dexuan Cui
2022-11-23 14:45 ` Michael Kelley (LINUX)
2022-11-28 0:58 ` Dexuan Cui
2022-11-28 1:20 ` Michael Kelley (LINUX)
2022-11-28 1:36 ` Dexuan Cui
2022-11-28 1:21 ` Sathyanarayanan Kuppuswamy
2022-11-28 1:55 ` Dexuan Cui
2022-11-28 15:22 ` Dave Hansen
2022-11-28 19:03 ` Dexuan Cui
2022-11-28 19:11 ` Dave Hansen
2022-11-28 19:37 ` Dexuan Cui
2022-11-28 19:48 ` Dave Hansen
2022-11-28 20:36 ` Dexuan Cui
2022-11-28 21:15 ` Dave Hansen
2022-11-28 21:53 ` Dexuan Cui
2022-11-21 19:51 ` [PATCH 6/6] Drivers: hv: vmbus: Support " Dexuan Cui
2023-01-06 11:00 ` Zhi Wang
2023-01-09 6:59 ` Dexuan Cui
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