From 1d7e6318afcf060f4cd6ae3681d29a6cddf294ff Mon Sep 17 00:00:00 2001 From: Amit Machhiwal Date: Fri, 18 Oct 2024 22:08:49 +0530 Subject: spapr: nested: Add support for DPDES SPR in GSB for TCG L0 The DPDES support for doorbell emulation and handling for KVM on PAPR guests was added in Linux via [1]. Subsequently, a new GSB (Guest State Buffer) element for DPDES was added in Linux; the same has been missing in TCG L0 implementation. Add support for DPDES register's APIv2 GSB element and required handling in `spapr_nested.c`. Currently, booting a KVM guest inside a QEMU TCG guest fails with the following crash. The crash occurs while handling the GUEST_RUN_VCPU hcall made in TCG L0. In the hcall handling path, map_and_getset_state() calls getset_state(), which, in turn, calls guest_state_request_check() to validate the GSR (Guest State Request) elements. During this process, guest_state_request_check() iterates over the GSR elements and receives a NULL return code from guest_state_element_type_find() for the type variable corresponding to the DPDES register's elemetn ID (which was unknown to TCG L0). Subsequently, getset_state() returns H_P3, ultimately leading to the hcall failure and causing the KVM guest to crash. KVM: unknown exit, hardware reason ffffffffffffffea [ ... KVM register dump ... ] Fix this by adding the required support in TCG L0 implementation of APIv2. [1] https://lore.kernel.org/all/20240605113913.83715-1-gautam@linux.ibm.com/ Fixes: 4a575f9a0567 ("spapr: nested: Initialize the GSB elements lookup table.") Suggested-by: Harsh Prateek Bora Signed-off-by: Amit Machhiwal Reviewed-by: Harsh Prateek Bora Signed-off-by: Nicholas Piggin --- hw/ppc/spapr_nested.c | 1 + include/hw/ppc/spapr_nested.h | 3 ++- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/hw/ppc/spapr_nested.c b/hw/ppc/spapr_nested.c index c02785756c..1b41c8fb8b 100644 --- a/hw/ppc/spapr_nested.c +++ b/hw/ppc/spapr_nested.c @@ -982,6 +982,7 @@ struct guest_state_element_type guest_state_element_types[] = { GUEST_STATE_ELEMENT_ENV_DW(GSB_VCPU_SPR_FSCR, fscr), GUEST_STATE_ELEMENT_ENV_W(GSB_VCPU_SPR_PSPB, pspb), GUEST_STATE_ELEMENT_ENV_DW(GSB_VCPU_SPR_CTRL, ctrl), + GUEST_STATE_ELEMENT_ENV_DW(GSB_VCPU_SPR_DPDES, dpdes), GUEST_STATE_ELEMENT_ENV_W(GSB_VCPU_SPR_VRSAVE, vrsave), GUEST_STATE_ELEMENT_ENV_DW(GSB_VCPU_SPR_DAR, dar), GUEST_STATE_ELEMENT_ENV_W(GSB_VCPU_SPR_DSISR, dsisr), diff --git a/include/hw/ppc/spapr_nested.h b/include/hw/ppc/spapr_nested.h index 93ef14adcc..3b5cd993c2 100644 --- a/include/hw/ppc/spapr_nested.h +++ b/include/hw/ppc/spapr_nested.h @@ -99,7 +99,8 @@ #define GSB_VCPU_SPR_HASHKEYR 0x1050 #define GSB_VCPU_SPR_HASHPKEYR 0x1051 #define GSB_VCPU_SPR_CTRL 0x1052 - /* RESERVED 0x1053 - 0x1FFF */ +#define GSB_VCPU_SPR_DPDES 0x1053 + /* RESERVED 0x1054 - 0x1FFF */ #define GSB_VCPU_SPR_CR 0x2000 #define GSB_VCPU_SPR_PIDR 0x2001 #define GSB_VCPU_SPR_DSISR 0x2002 -- cgit v1.2.3