From 98d204a990148e08dbbf99f356b11ab377e0fdf2 Mon Sep 17 00:00:00 2001 From: Arthur Hanson Rasmusson Date: Wed, 7 Oct 2026 12:03:02 -0400 Subject: vgsp: m86 - sticky gsp_phys_rmcall_gr_override_hex module parameter The override blob can now be supplied at load (hex string, <= 1 page) and is parsed at the first forwarded launch, so the minimal-kernel experiment no longer depends on a debugfs write racing the guest's launch. Also observed in the m86 attempt: after many failed launches the forwarded ring desynced (USERD GP_PUT rewound to 1 while the engine's GP_GET was 513; IQ2M sentinel intact, no FE fetch) - a fresh boot is required per experiment. --- kernel/gsp_phys_booter.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) (limited to 'kernel/gsp_phys_booter.c') diff --git a/kernel/gsp_phys_booter.c b/kernel/gsp_phys_booter.c index d7ba43d..ee433e1 100644 --- a/kernel/gsp_phys_booter.c +++ b/kernel/gsp_phys_booter.c @@ -15539,6 +15539,38 @@ static u64 gsp_phys_gr_pool_exhausted; /* m86: program-page override blob (see gsp-phys-gr-override). */ static u8 gsp_phys_gr_override[GSP_PHYS_PAGE_SIZE]; static u32 gsp_phys_gr_override_len; +static bool gsp_phys_gr_override_parsed; + +/* m86: parse the sticky hex override parameter once, before first use. */ +static void gsp_phys_gr_override_apply_param(void) +{ + const char *h = gsp_phys_rmcall_gr_override_hex_value(); + u32 n, i; + + if (gsp_phys_gr_override_parsed) + return; + gsp_phys_gr_override_parsed = true; + if (!h || !h[0] || READ_ONCE(gsp_phys_gr_override_len)) + return; + n = (u32)strlen(h); + if (n % 2 || n / 2 > GSP_PHYS_PAGE_SIZE) { + pr_warn("vgsp-boot: gr-override hex param ignored (bad length %u)\n", + n); + return; + } + for (i = 0; i < n; i += 2) { + unsigned int b; + + if (sscanf(h + i, "%2x", &b) != 1) { + pr_warn("vgsp-boot: gr-override hex param bad at %u\n", + i); + return; + } + gsp_phys_gr_override[i / 2] = (u8)b; + } + WRITE_ONCE(gsp_phys_gr_override_len, n / 2); + pr_info("vgsp-boot: gr-override hex param: %u bytes stored\n", n / 2); +} void gsp_phys_backend_gr_counters(u64 *submitted, u64 *ok, u64 *refused, u64 *timed_out, u64 *pool_exhausted) @@ -16114,6 +16146,7 @@ int gsp_phys_backend_guest_gr_submit(const struct gsp_phys_gr_submit *req, } gsp_phys_gr_submitted++; + gsp_phys_gr_override_apply_param(); mutex_lock(&gsp_phys_rm_lock); if (!gsp_phys_backend_gr_ready()) { mutex_unlock(&gsp_phys_rm_lock); -- cgit v1.2.3