Re: [PATCH v6 08/14] x86: Secure Launch kernel late boot stub

[Ross Philipson]

On 5/5/23 13:52, Simon Horman wrote:
> On Thu, May 04, 2023 at 02:50:17PM +0000, Ross Philipson wrote:
> > The routine slaunch_setup is called out of the x86 specific setup_arch
> > routine during early kernel boot. After determining what platform is
> > present, various operations specific to that platform occur. This
> > includes finalizing setting for the platform late launch and verifying
> > that memory protections are in place.
> >
> > For TXT, this code also reserves the original compressed kernel setup
> > area where the APs were left looping so that this memory cannot be used.
> >
> > Signed-off-by: Ross Philipson <ross.philipson@xxxxxxxxxx>
>
> Hi Ross,
>
> a few nits from my side.

Yup we will fix all of those.

Thanks
Ross

> > +/*
> > + * The TXT heap is too big to map all at once with early_ioremap
> > + * so it is done a table at a time.
> > + */
> > +static void __init *txt_early_get_heap_table(void __iomem *txt, u32 type,
> > +					     u32 bytes)
> > +{
> > +	u64 base, size, offset = 0;
> > +	void *heap;
> > +	int i;
> > +
> > +	if (type > TXT_SINIT_TABLE_MAX)
> > +		slaunch_txt_reset(txt,
> > +			"Error invalid table type for early heap walk\n",
> > +			SL_ERROR_HEAP_WALK);
>
> nit: the indentation should align to the opening '('.
>
> 		slaunch_txt_reset(txt,
> 				  "Error invalid table type for early heap walk\n",
> 				  SL_ERROR_HEAP_WALK);
>
> Likewise in a few other places in this patch.
>
> ...
>
> > +static void __init slaunch_txt_reserve_range(u64 base, u64 size)
> > +{
> > +	int type;
> > +
> > +	type = e820__get_entry_type(base, base + size - 1);
> > +	if (type == E820_TYPE_RAM) {
> > +		pr_info("memblock reserve base: %llx size: %llx\n", base, size);
> > +		memblock_reserve(base, size);
> > +	}
> > +}
> > +
> > +/*
> > + * For Intel, certain regions of memory must be marked as reserved by putting
> > + * them on the memblock reserved list if they are not already e820 reserved.
> > + * This includes:
> > + *  - The TXT HEAP
> > + *  - The ACM area
> > + *  - The TXT private register bank
> > + *  - The MDR list sent to the MLE by the ACM (see TXT specification)
> > + *  (Normally the above are properly reserved by firmware but if it was not
> > + *  done, reserve them now)
> > + *  - The AP wake block
> > + *  - TPM log external to the TXT heap
> > + *
> > + * Also if the low PMR doesn't cover all memory < 4G, any RAM regions above
> > + * the low PMR must be reservered too.
>
> nit: s/reservered/reserved/
>
> > + */
> > +static void __init slaunch_txt_reserve(void __iomem *txt)
> > +{
> > +	struct txt_sinit_memory_descriptor_record *mdr;
> > +	struct txt_sinit_mle_data *sinit_mle_data;
> > +	u64 base, size, heap_base, heap_size;
> > +	u32 mdrnum, mdroffset, mdrslen;
> > +	u32 field_offset, i;
> > +	void *mdrs;
> > +
> > +	base = TXT_PRIV_CONFIG_REGS_BASE;
> > +	size = TXT_PUB_CONFIG_REGS_BASE - TXT_PRIV_CONFIG_REGS_BASE;
> > +	slaunch_txt_reserve_range(base, size);
> > +
> > +	memcpy_fromio(&heap_base, txt + TXT_CR_HEAP_BASE, sizeof(heap_base));
> > +	memcpy_fromio(&heap_size, txt + TXT_CR_HEAP_SIZE, sizeof(heap_size));
> > +	slaunch_txt_reserve_range(heap_base, heap_size);
> > +
> > +	memcpy_fromio(&base, txt + TXT_CR_SINIT_BASE, sizeof(base));
> > +	memcpy_fromio(&size, txt + TXT_CR_SINIT_SIZE, sizeof(size));
> > +	slaunch_txt_reserve_range(base, size);
> > +
> > +	field_offset = offsetof(struct txt_sinit_mle_data,
> > +				sinit_vtd_dmar_table_size);
> > +	sinit_mle_data = txt_early_get_heap_table(txt, TXT_SINIT_MLE_DATA_TABLE,
> > +						  field_offset);
> > +
> > +	mdrnum = sinit_mle_data->num_of_sinit_mdrs;
> > +	mdroffset = sinit_mle_data->sinit_mdrs_table_offset;
> > +
> > +	txt_early_put_heap_table(sinit_mle_data, field_offset);
> > +
> > +	if (!mdrnum)
> > +		goto nomdr;
> > +
> > +	mdrslen = mdrnum * sizeof(struct txt_sinit_memory_descriptor_record);
> > +
> > +	mdrs = txt_early_get_heap_table(txt, TXT_SINIT_MLE_DATA_TABLE,
> > +					mdroffset + mdrslen - 8);
> > +
> > +	mdr = mdrs + mdroffset - 8;
> > +
> > +	for (i = 0; i < mdrnum; i++, mdr++) {
> > +		/* Spec says some entries can have length 0, ignore them */
> > +		if (mdr->type > 0 && mdr->length > 0)
> > +			slaunch_txt_reserve_range(mdr->address, mdr->length);
> > +	}
> > +
> > +	txt_early_put_heap_table(mdrs, mdroffset + mdrslen - 8);
> > +
> > +nomdr:
> > +	slaunch_txt_reserve_range(ap_wake_info.ap_wake_block,
> > +				  ap_wake_info.ap_wake_block_size);
> > +
> > +	/*
> > +	 * Earlier checks ensured that the event log was properly situated
> > +	 * either inside the TXT heap or outside. This is a check to see if the
> > +	 * event log needs to be reserved. If it is in the TXT heap, it is
> > +	 * already reserved.
> > +	 */
> > +	if (evtlog_addr < heap_base || evtlog_addr > (heap_base + heap_size))
> > +		slaunch_txt_reserve_range(evtlog_addr, evtlog_size);
> > +
> > +	for (i = 0; i < e820_table->nr_entries; i++) {
> > +		base = e820_table->entries[i].addr;
> > +		size = e820_table->entries[i].size;
> > +		if ((base >= vtd_pmr_lo_size) && (base < 0x100000000ULL))
>
> nit: unnecessary parentheses
>
> > +			slaunch_txt_reserve_range(base, size);
> > +		else if ((base < vtd_pmr_lo_size) &&
> > +			 (base + size > vtd_pmr_lo_size))
> > +			slaunch_txt_reserve_range(vtd_pmr_lo_size,
> > +						  base + size - vtd_pmr_lo_size);
> > +	}
> > +}
> > +
> > +/*
> > + * TXT stashes a safe copy of the DMAR ACPI table to prevent tampering.
> > + * It is stored in the TXT heap. Fetch it from there and make it available
> > + * to the IOMMU driver.
> > + */
> > +static void __init slaunch_copy_dmar_table(void __iomem *txt)
> > +{
> > +	struct txt_sinit_mle_data *sinit_mle_data;
> > +	u32 field_offset, dmar_size, dmar_offset;
> > +	void *dmar;
> > +
> > +	memset(&txt_dmar, 0, PAGE_SIZE);
> > +
> > +	field_offset = offsetof(struct txt_sinit_mle_data,
> > +				processor_scrtm_status);
> > +	sinit_mle_data = txt_early_get_heap_table(txt, TXT_SINIT_MLE_DATA_TABLE,
> > +						  field_offset);
> > +
> > +	dmar_size = sinit_mle_data->sinit_vtd_dmar_table_size;
> > +	dmar_offset = sinit_mle_data->sinit_vtd_dmar_table_offset;
> > +
> > +	txt_early_put_heap_table(sinit_mle_data, field_offset);
> > +
> > +	if (!dmar_size || !dmar_offset)
> > +		slaunch_txt_reset(txt,
> > +				  "Error invalid DMAR table values\n",
> > +				  SL_ERROR_HEAP_INVALID_DMAR);
> > +
> > +	if (unlikely(dmar_size > PAGE_SIZE))
> > +		slaunch_txt_reset(txt,
> > +				  "Error DMAR too big to store\n",
> > +				  SL_ERROR_HEAP_DMAR_SIZE);
> > +
> > +
>
> nit: one blank line is enough
>
> > +	dmar = txt_early_get_heap_table(txt, TXT_SINIT_MLE_DATA_TABLE,
> > +					dmar_offset + dmar_size - 8);
> > +	if (!dmar)
> > +		slaunch_txt_reset(txt,
> > +				  "Error early_ioremap of DMAR\n",
> > +				  SL_ERROR_HEAP_DMAR_MAP);
> > +
> > +	memcpy(&txt_dmar[0], dmar + dmar_offset - 8, dmar_size);
> > +
> > +	txt_early_put_heap_table(dmar, dmar_offset + dmar_size - 8);
> > +}
>
> ...
>
> > +/*
> > + * Intel TXT specific late stub setup and validation.
> > + */
> > +void __init slaunch_setup_txt(void)
> > +{
> > +	u64 one = TXT_REGVALUE_ONE, val;
> > +	void __iomem *txt;
> > +
> > +	if (!boot_cpu_has(X86_FEATURE_SMX))
> > +		return;
> > +
> > +	/*
> > +	 * If booted through secure launch entry point, the loadflags
> > +	 * option will be set.
> > +	 */
> > +	if (!(boot_params.hdr.loadflags & SLAUNCH_FLAG))
> > +		return;
> > +
> > +	/*
> > +	 * See if SENTER was done by reading the status register in the
> > +	 * public space. If the public register space cannot be read, TXT may
> > +	 * be disabled.
> > +	 */
> > +	txt = early_ioremap(TXT_PUB_CONFIG_REGS_BASE,
> > +			    TXT_NR_CONFIG_PAGES * PAGE_SIZE);
> > +	if (!txt)
> > +		return;
> > +
> > +	memcpy_fromio(&val, txt + TXT_CR_STS, sizeof(val));
> > +	early_iounmap(txt, TXT_NR_CONFIG_PAGES * PAGE_SIZE);
> > +
> > +	/* SENTER should have been done */
> > +	if (!(val & TXT_SENTER_DONE_STS))
> > +		panic("Error TXT.STS SENTER_DONE not set\n");
> > +
> > +	/* SEXIT should have been cleared */
> > +	if (val & TXT_SEXIT_DONE_STS)
> > +		panic("Error TXT.STS SEXIT_DONE set\n");
> > +
> > +	/* Now we want to use the private register space */
> > +	txt = early_ioremap(TXT_PRIV_CONFIG_REGS_BASE,
> > +			    TXT_NR_CONFIG_PAGES * PAGE_SIZE);
> > +	if (!txt) {
> > +		/* This is really bad, no where to go from here */
> > +		panic("Error early_ioremap of TXT priv registers\n");
> > +	}
> > +
> > +	/*
> > +	 * Try to read the Intel VID from the TXT private registers to see if
> > +	 * TXT measured launch happened properly and the private space is
> > +	 * available.
> > +	 */
> > +	memcpy_fromio(&val, txt + TXT_CR_DIDVID, sizeof(val));
> > +	if ((val & 0xffff) != 0x8086) {
> > +		/*
> > +		 * Can't do a proper TXT reset since it appears something is
> > +		 * wrong even though SENTER happened and it should be in SMX
> > +		 * mode.
> > +		 */
> > +		panic("Invalid TXT vendor ID, not in SMX mode\n");
> > +	}
> > +
> > +	/* Set flags so subsequent code knows the status of the launch */
> > +	sl_flags |= (SL_FLAG_ACTIVE|SL_FLAG_ARCH_TXT);
>
> nit: spaces around '|'
>
> ...