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bhyve: read out graphics stolen memory address and size

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This is the first step to emulate the graphics stolen memory register.

Note that the graphics stolen memory is somehow confusing. On the one
hand the Intel Open Source HD Graphics Programmers' Reference Manual
states that it's only GPU accessible. As the CPU can't access the area,
the guest shouldn't need it. On the other hand, the Intel GOP driver
refuses to work properly, if it's not set to a proper address.

Intel itself maps it into the guest by EPT [1]. At the moment, we're not
aware of any situation where this EPT mapping is required, so we don't
do it yet.

Intel also states that the Windows driver for Tiger Lake reads the
address of the graphics stolen memory [2]. As the GVT-d code doesn't
support Tiger Lake in its first implementation, we can't check how it
behaves. We should keep an eye on it.

[1]
e28d6fbfdf/devicemodel/hw/pci/passthrough.c (L655-L657)
[2]
e28d6fbfdf/devicemodel/hw/pci/passthrough.c (L626-L629)

Reviewed by:		markj
MFC after:		1 week
Sponsored by:		Beckhoff Automation GmbH & Co. KG
Differential Revision:	https://reviews.freebsd.org/D40039
This commit is contained in:
Corvin Köhne 2023-05-11 10:53:15 +02:00
parent 90c3a1b662
commit 4a9bf50f40
No known key found for this signature in database
GPG Key ID: D854DA56315E026A
1 changed files with 72 additions and 1 deletions
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73
usr.sbin/bhyve/pci_gvt-d.c
View File

@ -6,6 +6,9 @@
*/
#include <sys/types.h>
#include <sys/sysctl.h>
#include <err.h>
#include <dev/pci/pcireg.h>
@ -16,6 +19,8 @@
#define PCI_VENDOR_INTEL 0x8086
#define GVT_D_MAP_GSM 0
static int
gvt_d_probe(struct pci_devinst *const pi)
{
@ -36,12 +41,78 @@ gvt_d_probe(struct pci_devinst *const pi)
return (0);
}
/*
* Note that the graphics stolen memory is somehow confusing. On the one hand
* the Intel Open Source HD Graphics Programmers' Reference Manual states that
* it's only GPU accessible. As the CPU can't access the area, the guest
* shouldn't need it. On the other hand, the Intel GOP driver refuses to work
* properly, if it's not set to a proper address.
*
* Intel itself maps it into the guest by EPT [1]. At the moment, we're not
* aware of any situation where this EPT mapping is required, so we don't do it
* yet.
*
* Intel also states that the Windows driver for Tiger Lake reads the address of
* the graphics stolen memory [2]. As the GVT-d code doesn't support Tiger Lake
* in its first implementation, we can't check how it behaves. We should keep an
* eye on it.
*
* [1]
* https://github.com/projectacrn/acrn-hypervisor/blob/e28d6fbfdfd556ff1bc3ff330e41d4ddbaa0f897/devicemodel/hw/pci/passthrough.c#L655-L657
* [2]
* https://github.com/projectacrn/acrn-hypervisor/blob/e28d6fbfdfd556ff1bc3ff330e41d4ddbaa0f897/devicemodel/hw/pci/passthrough.c#L626-L629
*/
static int
gvt_d_init(struct pci_devinst *const pi __unused, nvlist_t *const nvl __unused)
gvt_d_setup_gsm(struct pci_devinst *const pi)
{
struct passthru_softc *sc;
struct passthru_mmio_mapping *gsm;
size_t sysctl_len;
int error;
sc = pi->pi_arg;
gsm = passthru_get_mmio(sc, GVT_D_MAP_GSM);
if (gsm == NULL) {
warnx("%s: Unable to access gsm", __func__);
return (-1);
}
sysctl_len = sizeof(gsm->hpa);
error = sysctlbyname("hw.intel_graphics_stolen_base", &gsm->hpa,
&sysctl_len, NULL, 0);
if (error) {
warn("%s: Unable to get graphics stolen memory base",
__func__);
return (-1);
}
sysctl_len = sizeof(gsm->len);
error = sysctlbyname("hw.intel_graphics_stolen_size", &gsm->len,
&sysctl_len, NULL, 0);
if (error) {
warn("%s: Unable to get graphics stolen memory length",
__func__);
return (-1);
}
gsm->hva = NULL; /* unused */
return (0);
}
static int
gvt_d_init(struct pci_devinst *const pi, nvlist_t *const nvl __unused)
{
int error;
if ((error = gvt_d_setup_gsm(pi)) != 0) {
warnx("%s: Unable to setup Graphics Stolen Memory", __func__);
goto done;
}
done:
return (error);
}
static void
gvt_d_deinit(struct pci_devinst *const pi __unused)
{