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From: Alexander Graf <agraf@csgraf.de>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: "Eduardo Habkost" <ehabkost@redhat.com>,
	"Philippe Mathieu-Daudé" <philmd@redhat.com>,
	"Richard Henderson" <richard.henderson@linaro.org>,
	"QEMU Developers" <qemu-devel@nongnu.org>,
	"Cameron Esfahani" <dirty@apple.com>,
	"Roman Bolshakov" <r.bolshakov@yadro.com>,
	qemu-arm <qemu-arm@nongnu.org>, "Frank Yang" <lfy@google.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Peter Collingbourne" <pcc@google.com>
Subject: Re: [PATCH v8 19/19] hvf: arm: Handle Windows 10 SMC call
Date: Sun, 27 Jun 2021 23:07:55 +0200	[thread overview]
Message-ID: <ee7df565-7b43-f1b3-aee7-de67167acf4c@csgraf.de> (raw)
In-Reply-To: <CAFEAcA880Kgb5GtKEQQpnD=fAwfm1Cs1Sjfc4L5S0ETkjm-CWA@mail.gmail.com>


On 15.06.21 11:31, Peter Maydell wrote:
> On Wed, 19 May 2021 at 21:23, Alexander Graf <agraf@csgraf.de> wrote:
>> Windows 10 calls an SMCCC call via SMC unconditionally on boot. It lives
>> in the trusted application call number space, but its purpose is unknown.
>>
>> In our current SMC implementation, we inject a UDEF for unknown SMC calls,
>> including this one. However, Windows breaks on boot when we do this. Instead,
>> let's return an error code.
>>
>> With this patch applied I can successfully boot the current Windows 10
>> Insider Preview in HVF.
>>
>> Signed-off-by: Alexander Graf <agraf@csgraf.de>
>>
>> ---
>>
>> v7 -> v8:
>>
>>   - fix checkpatch
>> ---
>>  target/arm/hvf/hvf.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/target/arm/hvf/hvf.c b/target/arm/hvf/hvf.c
>> index 65c33e2a14..be670af578 100644
>> --- a/target/arm/hvf/hvf.c
>> +++ b/target/arm/hvf/hvf.c
>> @@ -931,6 +931,10 @@ int hvf_vcpu_exec(CPUState *cpu)
>>          cpu_synchronize_state(cpu);
>>          if (!hvf_handle_psci_call(cpu)) {
>>              advance_pc = true;
>> +        } else if (env->xregs[0] == QEMU_SMCCC_TC_WINDOWS10_BOOT) {
>> +            /* This special SMC is called by Windows 10 on boot. Return error */
>> +            env->xregs[0] = -1;
>> +            advance_pc = true;
>>          } else {
>>              trace_hvf_unknown_smc(env->xregs[0]);
>>              hvf_raise_exception(env, EXCP_UDEF, syn_uncategorized());
> Where can I find documentation on what this SMC call is and what
> it's supposed to do ?


It's 0xc3000001 which according to the SMCCC spec [1] means OR'ed values
of the following:

0x80000000 = Fast Call
0x40000000 = SMC64
0x03000000 = OEM Service Calls
0x00000001 = Function number 1

So, uh. I'm not sure how to answer the question above. I don't have
source level access to Windows to read what the call is supposed to do
:). But it's definitely calling something OEM specific that it really
shouldn't be callling.

Reading the SMCCC spec section 5.2, unknown SMCCC calls should return
-1. It advises against probing by just calling them, but does not
specify any other fault behavior than the -1 return (such as the #UDEF
we inject in TCG).


Alex

[1] https://developer.arm.com/documentation/den0028/latest



  reply	other threads:[~2021-06-27 21:08 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-19 20:22 [PATCH v8 00/19] hvf: Implement Apple Silicon Support Alexander Graf
2021-05-19 20:22 ` [PATCH v8 01/19] hvf: Move assert_hvf_ok() into common directory Alexander Graf
2021-05-27 10:00   ` Sergio Lopez
2021-05-19 20:22 ` [PATCH v8 02/19] hvf: Move vcpu thread functions " Alexander Graf
2021-05-27 10:01   ` Sergio Lopez
2021-05-19 20:22 ` [PATCH v8 03/19] hvf: Move cpu " Alexander Graf
2021-05-27 10:02   ` Sergio Lopez
2021-05-19 20:22 ` [PATCH v8 04/19] hvf: Move hvf internal definitions into common header Alexander Graf
2021-05-27 10:04   ` Sergio Lopez
2021-05-19 20:22 ` [PATCH v8 05/19] hvf: Make hvf_set_phys_mem() static Alexander Graf
2021-05-27 10:06   ` Sergio Lopez
2021-05-19 20:22 ` [PATCH v8 06/19] hvf: Remove use of hv_uvaddr_t and hv_gpaddr_t Alexander Graf
2021-05-27 10:07   ` Sergio Lopez
2021-05-19 20:22 ` [PATCH v8 07/19] hvf: Split out common code on vcpu init and destroy Alexander Graf
2021-05-27 10:09   ` Sergio Lopez
2021-05-19 20:22 ` [PATCH v8 08/19] hvf: Use cpu_synchronize_state() Alexander Graf
2021-05-27 10:15   ` Sergio Lopez
2021-05-19 20:22 ` [PATCH v8 09/19] hvf: Make synchronize functions static Alexander Graf
2021-05-27 10:15   ` Sergio Lopez
2021-05-19 20:22 ` [PATCH v8 10/19] hvf: Remove hvf-accel-ops.h Alexander Graf
2021-05-27 10:16   ` Sergio Lopez
2021-05-19 20:22 ` [PATCH v8 11/19] hvf: Introduce hvf vcpu struct Alexander Graf
2021-05-27 10:18   ` Sergio Lopez
2021-05-19 20:22 ` [PATCH v8 12/19] hvf: Simplify post reset/init/loadvm hooks Alexander Graf
2021-05-27 10:20   ` Sergio Lopez
2021-05-19 20:22 ` [PATCH v8 13/19] hvf: Add Apple Silicon support Alexander Graf
2021-05-27 10:55   ` Sergio Lopez
2021-06-15 10:21   ` Peter Maydell
2021-06-27 20:40     ` Alexander Graf
2021-05-19 20:22 ` [PATCH v8 14/19] arm/hvf: Add a WFI handler Alexander Graf
2021-05-27 10:53   ` Sergio Lopez
2021-06-15 10:38   ` Peter Maydell
2021-05-19 20:22 ` [PATCH v8 15/19] hvf: arm: Implement -cpu host Alexander Graf
2021-05-27 11:18   ` Sergio Lopez
2021-06-15 10:56   ` Peter Maydell
2021-09-12 20:23     ` Alexander Graf
2021-09-13  8:28       ` Peter Maydell
2021-09-13 10:46         ` Alexander Graf
2021-09-13 10:52           ` Peter Maydell
2021-09-13 11:46             ` Alexander Graf
2021-09-13 11:48               ` Peter Maydell
2021-09-13 11:55                 ` Alexander Graf
2021-05-19 20:22 ` [PATCH v8 16/19] hvf: arm: Implement PSCI handling Alexander Graf
2021-05-27 11:20   ` Sergio Lopez
2021-06-15 12:54   ` Peter Maydell
2021-09-12 20:36     ` Alexander Graf
2021-09-12 21:20       ` Richard Henderson
2021-09-12 21:37         ` Alexander Graf
2021-09-12 21:40           ` Richard Henderson
2021-09-13 10:06             ` Alexander Graf
2021-09-13 10:30               ` Philippe Mathieu-Daudé
2021-05-19 20:22 ` [PATCH v8 17/19] arm: Add Hypervisor.framework build target Alexander Graf
2021-05-27 11:20   ` Sergio Lopez
2021-06-15 10:59   ` Peter Maydell
2021-05-19 20:22 ` [PATCH v8 18/19] arm: Enable Windows 10 trusted SMCCC boot call Alexander Graf
2021-05-27 11:21   ` Sergio Lopez
2021-06-15 11:02   ` Peter Maydell
2021-06-27 21:12     ` Alexander Graf
2021-05-19 20:22 ` [PATCH v8 19/19] hvf: arm: Handle Windows 10 SMC call Alexander Graf
2021-05-27 11:22   ` Sergio Lopez
2021-06-15  9:31   ` Peter Maydell
2021-06-27 21:07     ` Alexander Graf [this message]
2021-05-19 20:45 ` [PATCH v8 00/19] hvf: Implement Apple Silicon Support no-reply
2021-06-03 13:43 ` Peter Maydell
2021-06-03 13:53   ` Alexander Graf
2021-06-15 12:54   ` Peter Maydell

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