From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Dexuan Cui <decui@microsoft.com>
Cc: ak@linux.intel.com, arnd@arndb.de, bp@alien8.de,
brijesh.singh@amd.com, dan.j.williams@intel.com,
dave.hansen@linux.intel.com, haiyangz@microsoft.com,
hpa@zytor.com, jane.chu@oracle.com,
kirill.shutemov@linux.intel.com, kys@microsoft.com,
linux-arch@vger.kernel.org, linux-hyperv@vger.kernel.org,
luto@kernel.org, mingo@redhat.com, peterz@infradead.org,
rostedt@goodmis.org, sathyanarayanan.kuppuswamy@linux.intel.com,
seanjc@google.com, tglx@linutronix.de, tony.luck@intel.com,
wei.liu@kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/6] x86/tdx: Retry TDVMCALL_MAP_GPA() when needed
Date: Tue, 22 Nov 2022 03:01:00 +0300 [thread overview]
Message-ID: <20221122000100.bizske6iltfgdwcu@box.shutemov.name> (raw)
In-Reply-To: <20221121195151.21812-3-decui@microsoft.com>
On Mon, Nov 21, 2022 at 11:51:47AM -0800, Dexuan Cui wrote:
> GHCI spec for TDX 1.0 says that the MapGPA call may fail with the R10
> error code = TDG.VP.VMCALL_RETRY (1), and the guest must retry this
> operation for the pages in the region starting at the GPA specified
> in R11.
>
> When a TDX guest runs on Hyper-V, Hyper-V returns the retry error
> when hyperv_init() -> swiotlb_update_mem_attributes() ->
> set_memory_decrypted() decrypts up to 1GB of swiotlb bounce buffers.
>
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
> ---
> arch/x86/coco/tdx/tdx.c | 65 +++++++++++++++++++++++++++++++++++++----
> 1 file changed, 59 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
> index 3fee96931ff5..46971cc7d006 100644
> --- a/arch/x86/coco/tdx/tdx.c
> +++ b/arch/x86/coco/tdx/tdx.c
> @@ -20,6 +20,8 @@
> /* TDX hypercall Leaf IDs */
> #define TDVMCALL_MAP_GPA 0x10001
>
> +#define TDVMCALL_STATUS_RETRY 1
> +
> /* MMIO direction */
> #define EPT_READ 0
> #define EPT_WRITE 1
> @@ -52,6 +54,25 @@ static inline u64 _tdx_hypercall(u64 fn, u64 r12, u64 r13, u64 r14, u64 r15)
> return __tdx_hypercall(&args, 0);
> }
>
> +static inline u64 _tdx_hypercall_output_r11(u64 fn, u64 r12, u64 r13, u64 r14,
> + u64 r15, u64 *r11)
> +{
> + struct tdx_hypercall_args args = {
> + .r10 = TDX_HYPERCALL_STANDARD,
> + .r11 = fn,
> + .r12 = r12,
> + .r13 = r13,
> + .r14 = r14,
> + .r15 = r15,
> + };
> +
> + u64 ret;
> +
> + ret = __tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT);
> + *r11 = args.r11;
> + return ret;
> +}
> +
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?
> /* 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?
> + 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?
> +
> + start = r11;
> +
> + /* Set the shared (decrypted) bit. */
> + if (!enc)
> + start |= cc_mkdec(0);
> + }
> +
> + return !ret;
> +}
> +
> /*
> * Inform the VMM of the guest's intent for this physical page: shared with
> * the VMM or private to the guest. The VMM is expected to change its mapping
> @@ -707,12 +765,7 @@ static bool tdx_enc_status_changed(unsigned long vaddr, int numpages, bool enc)
> end |= cc_mkdec(0);
> }
>
> - /*
> - * 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>"
> - */
> - if (_tdx_hypercall(TDVMCALL_MAP_GPA, start, end - start, 0, 0))
> + if (!tdx_map_gpa(start, end, enc))
> return false;
>
> /* private->shared conversion requires only MapGPA call */
> --
> 2.25.1
>
--
Kiryl Shutsemau / Kirill A. Shutemov
next prev parent reply other threads:[~2022-11-22 0:01 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 [this message]
2022-11-23 3:27 ` Dexuan Cui
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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